diff --git a/src/Configuration/ServerOptions.cs b/src/Configuration/ServerOptions.cs
index 8552ee1..0d20e2c 100644
--- a/src/Configuration/ServerOptions.cs
+++ b/src/Configuration/ServerOptions.cs
@@ -26,4 +26,10 @@ public sealed class DataOptions
     public string LatestMasterDataVersion { get; init; } = string.Empty;
     public string UserDataPath { get; init; } = string.Empty;
     public string MasterDataPath { get; init; } = string.Empty;
+    
+    /// <summary>
+    /// Path to the JSON file used to persist user data between server restarts.
+    /// If relative, resolved against the application base directory.
+    /// </summary>
+    public string UserDatabase { get; init; } = "userdata.json";
 }
diff --git a/src/Data/UserDataDiffBuilder.cs b/src/Data/UserDataDiffBuilder.cs
index 5fc0fd1..efc1954 100644
--- a/src/Data/UserDataDiffBuilder.cs
+++ b/src/Data/UserDataDiffBuilder.cs
@@ -83,11 +83,11 @@ public static class UserDataDiffBuilder
 
     /// <summary>
     /// Computes only the tables that changed since the snapshot.
-    /// Use this for incremental API responses (e.g. SetUserName, GameStart).
+    /// Use this for incremental API responses (e.g. SetUserName).
     /// </summary>
     public static Dictionary<string, DiffData> Delta(Dictionary<string, string> before, DarkUserMemoryDatabase db)
     {
-        var diff = new Dictionary<string, DiffData>();
+        Dictionary<string, DiffData> diff = [];
         foreach (var (table, serialize) in Serializers)
         {
             var afterJson = serialize(db);
diff --git a/src/Data/UserDataStore.cs b/src/Data/UserDataStore.cs
index b9f4499..d58cd71 100644
--- a/src/Data/UserDataStore.cs
+++ b/src/Data/UserDataStore.cs
@@ -1,5 +1,6 @@
 using MariesWonderland.Models.Entities;
 using MariesWonderland.Models.Type;
+using System.Text.Json;
 
 namespace MariesWonderland.Data;
 
@@ -63,6 +64,58 @@ public class UserDataStore
 
     public IReadOnlyDictionary<long, DarkUserMemoryDatabase> All => _users;
 
+    /// <summary>
+    /// Serialize all user data to a JSON file on disk.
+    /// </summary>
+    public void Save(string filePath)
+    {
+        UserDataSnapshot snapshot = new()
+        {
+            Users = _users,
+            UuidToUserId = _uuidToUserId,
+            Sessions = _sessions.Values.ToList()
+        };
+
+        JsonSerializerOptions options = new()
+        {
+            WriteIndented = true
+        };
+
+        string json = JsonSerializer.Serialize(snapshot, options);
+        File.WriteAllText(filePath, json);
+    }
+
+    /// <summary>
+    /// Deserialize user data from a JSON file on disk, replacing the current in-memory state.
+    /// Returns the number of users loaded.
+    /// </summary>
+    public int Load(string filePath)
+    {
+        if (!File.Exists(filePath))
+            return 0;
+
+        string json = File.ReadAllText(filePath);
+        UserDataSnapshot? snapshot = JsonSerializer.Deserialize<UserDataSnapshot>(json);
+
+        if (snapshot is null)
+            return 0;
+
+        _users.Clear();
+        _uuidToUserId.Clear();
+        _sessions.Clear();
+
+        foreach (var (userId, db) in snapshot.Users)
+            _users[userId] = db;
+
+        foreach (var (uuid, userId) in snapshot.UuidToUserId)
+            _uuidToUserId[uuid] = userId;
+
+        foreach (UserSession session in snapshot.Sessions)
+            _sessions[session.SessionKey] = session;
+
+        return _users.Count;
+    }
+
     private static long GenerateUserId()
     {
         // Random 19-digit positive long (range: 1e18 to long.MaxValue)
@@ -137,3 +190,13 @@ public class UserDataStore
     }
 }
 
+/// <summary>
+/// Serializable snapshot of all user data for persistence.
+/// </summary>
+file record UserDataSnapshot
+{
+    public Dictionary<long, DarkUserMemoryDatabase> Users { get; init; } = [];
+    public Dictionary<string, long> UuidToUserId { get; init; } = [];
+    public List<UserSession> Sessions { get; init; } = [];
+}
+
diff --git a/src/Extensions/HttpApiExtensions.cs b/src/Extensions/HttpApiExtensions.cs
index f9571b8..9866321 100644
--- a/src/Extensions/HttpApiExtensions.cs
+++ b/src/Extensions/HttpApiExtensions.cs
@@ -1,4 +1,5 @@
 using MariesWonderland.Configuration;
+using MariesWonderland.Data;
 using MariesWonderland.Http;
 using Microsoft.Extensions.Options;
 using System.Text;
@@ -17,12 +18,46 @@ public static class HttpApiExtensions
         string assetDatabaseBasePath = options.Paths.AssetDatabase;
         string masterDatabaseBasePath = options.Paths.MasterDatabase;
         string resourcesBaseUrl = options.Paths.ResourcesBaseUrl;
+        string userDatabasePath = Path.IsPathRooted(options.Data.UserDatabase)
+            ? options.Data.UserDatabase
+            : Path.Combine(AppContext.BaseDirectory, options.Data.UserDatabase);
 
         ILogger<AssetDatabase> assetLogger = app.Services.GetRequiredService<ILoggerFactory>().CreateLogger<AssetDatabase>();
         AssetDatabase assetDb = new(assetDatabaseBasePath, assetLogger);
 
         app.MapGet("/", () => "Marie's Wonderland is open for business :marie:");
 
+        // Debug endpoints for manual save/load
+        app.MapGet("/debug/save", () =>
+        {
+            try
+            {
+                UserDataStore store = app.Services.GetRequiredService<UserDataStore>();
+                store.Save(userDatabasePath);
+                return Results.Ok($"Saved {store.All.Count} users to {userDatabasePath}");
+            }
+            catch (Exception ex)
+            {
+                return Results.Problem($"Save failed: {ex.Message}");
+            }
+        });
+
+        app.MapGet("/debug/load", () =>
+        {
+            try
+            {
+                UserDataStore store = app.Services.GetRequiredService<UserDataStore>();
+                int count = store.Load(userDatabasePath);
+                return count > 0
+                    ? Results.Ok($"Loaded {count} users from {userDatabasePath}")
+                    : Results.Ok("No save file found.");
+            }
+            catch (Exception ex)
+            {
+                return Results.Problem($"Load failed: {ex.Message}");
+            }
+        });
+
         // ToS. Expects the version wrapped in delimiters like "###123###".
         app.MapGet("/web/static/{languagePath}/terms/termsofuse", (string languagePath) => $"<html><head><title>Terms of Service</title></head><body><h1>Terms of Service</h1><p>Language: {languagePath}</p><p>Version: ###123###</p></body></html>");
 
diff --git a/src/Http/AssetDatabase.cs b/src/Http/AssetDatabase.cs
index 47d1bf3..a145598 100644
--- a/src/Http/AssetDatabase.cs
+++ b/src/Http/AssetDatabase.cs
@@ -8,7 +8,14 @@ namespace MariesWonderland.Http;
 
 /// <summary>
 /// Resolves asset bundle/resource requests by parsing list.bin protobuf indexes and info.json alias maps.
-/// Tracks the last-served list.bin revision per client IP so asset requests use the matching revision.
+///
+/// <para>
+/// Asset revisions are deltas, but revision 0 is a complete superset: it contains every objectId
+/// that appears across all 818 revisions (confirmed by exhaustive analysis). Later revisions carry
+/// updated versions of existing assets, not new ones. <see cref="Resolve"/> therefore checks the
+/// client's current revision first, then falls back to revision 0 — a single 25 MB index that
+/// covers the entire asset catalogue.
+/// </para>
 /// </summary>
 public sealed class AssetDatabase(string basePath, ILogger<AssetDatabase> logger)
 {
@@ -35,9 +42,21 @@ public sealed class AssetDatabase(string basePath, ILogger<AssetDatabase> logger
     /// Resolves an asset request to ordered file-path candidates.
     /// Caller should try each candidate in order, validating size and MD5, and serve the first valid one.
     /// </summary>
+    /// <remarks>
+    /// The client's current revision is checked first. If the objectId is not present (e.g. a
+    /// recent revision carries only updated entries, not the full catalogue), revision 0 is used
+    /// as the fallback. Revision 0 is a confirmed superset of all objectIds across every revision.
+    /// </remarks>
     public IEnumerable<AssetCandidate> Resolve(string clientIp, string assetType, string objectId)
     {
         string revision = _clientRevisions.TryGetValue(clientIp, out string? rev) ? rev : _lastKnownRevision;
+
+        // If the objectId isn't in the client's current revision, fall back to revision 0.
+        // Revision 0 is a complete superset — every objectId in the game is present there.
+        Dictionary<string, ListBinEntry>? currentIndex = LoadListBinIndex(revision);
+        if ((currentIndex is null || !currentIndex.ContainsKey(objectId)) && revision != "0")
+            revision = "0";
+
         return ResolveForRevision(revision, assetType, objectId);
     }
 
diff --git a/src/Models/Type/QuestStateType.cs b/src/Models/Type/QuestStateType.cs
new file mode 100644
index 0000000..db88314
--- /dev/null
+++ b/src/Models/Type/QuestStateType.cs
@@ -0,0 +1,9 @@
+namespace MariesWonderland.Models.Type;
+
+public enum QuestStateType
+{
+    UNKNOWN = 0,
+    ACTIVE = 1,
+    CLEARED = 2,
+    CHALLENGE = 4,
+}
diff --git a/src/Models/Type/SystemLanguage.cs b/src/Models/Type/SystemLanguage.cs
new file mode 100644
index 0000000..6c8c35a
--- /dev/null
+++ b/src/Models/Type/SystemLanguage.cs
@@ -0,0 +1,48 @@
+namespace MariesWonderland.Models.Type;
+
+public enum SystemLanguage
+{
+    Afrikaans = 0,
+    Arabic = 1,
+    Basque = 2,
+    Belarusian = 3,
+    Bulgarian = 4,
+    Catalan = 5,
+    Chinese = 6,
+    Czech = 7,
+    Danish = 8,
+    Dutch = 9,
+    English = 10,
+    Estonian = 11,
+    Faroese = 12,
+    Finnish = 13,
+    French = 14,
+    German = 15,
+    Greek = 16,
+    Hebrew = 17,
+    Icelandic = 19,
+    Indonesian = 20,
+    Italian = 21,
+    Japanese = 22,
+    Korean = 23,
+    Latvian = 24,
+    Lithuanian = 25,
+    Norwegian = 26,
+    Polish = 27,
+    Portuguese = 28,
+    Romanian = 29,
+    Russian = 30,
+    SerboCroatian = 31,
+    Slovak = 32,
+    Slovenian = 33,
+    Spanish = 34,
+    Swedish = 35,
+    Thai = 36,
+    Turkish = 37,
+    Ukrainian = 38,
+    Vietnamese = 39,
+    ChineseSimplified = 40,
+    ChineseTraditional = 41,
+    Unknown = 42,
+    Hungarian = 18
+}
diff --git a/src/Program.cs b/src/Program.cs
index 573c483..94e60aa 100644
--- a/src/Program.cs
+++ b/src/Program.cs
@@ -1,5 +1,8 @@
+using MariesWonderland.Configuration;
+using MariesWonderland.Data;
 using MariesWonderland.Extensions;
 using Microsoft.AspNetCore.Server.Kestrel.Core;
+using Microsoft.Extensions.Options;
 
 namespace MariesWonderland;
 
@@ -26,6 +29,19 @@ public static class Program
 
         var app = builder.Build();
 
+        // Load user data on startup
+        UserDataStore userDataStore = app.Services.GetRequiredService<UserDataStore>();
+        ServerOptions serverOptions = app.Services.GetRequiredService<IOptions<ServerOptions>>().Value;
+        string userDatabasePath = Path.IsPathRooted(serverOptions.Data.UserDatabase)
+            ? serverOptions.Data.UserDatabase
+            : Path.Combine(AppContext.BaseDirectory, serverOptions.Data.UserDatabase);
+
+        int loadedUsers = userDataStore.Load(userDatabasePath);
+        if (loadedUsers > 0)
+        {
+            app.Logger.LogInformation("Loaded {Count} users from {Path}", loadedUsers, userDatabasePath);
+        }
+
         app.MapGrpcServices();
         app.MapHttpApis();
 
diff --git a/src/Services/GameplayService.cs b/src/Services/GameplayService.cs
index ea75f4c..f7251e7 100644
--- a/src/Services/GameplayService.cs
+++ b/src/Services/GameplayService.cs
@@ -1,5 +1,6 @@
-using MariesWonderland.Proto.GamePlay;
 using Grpc.Core;
+using MariesWonderland.Proto.Gacha;
+using MariesWonderland.Proto.GamePlay;
 
 namespace MariesWonderland.Services;
 
@@ -7,6 +8,16 @@ public class GameplayService : MariesWonderland.Proto.GamePlay.GameplayService.G
 {
     public override Task<CheckBeforeGamePlayResponse> CheckBeforeGamePlay(CheckBeforeGamePlayRequest request, ServerCallContext context)
     {
-        return Task.FromResult(new CheckBeforeGamePlayResponse());
+        CheckBeforeGamePlayResponse response = new()
+        {
+            IsExistUnreadPop = true
+        };
+        response.MenuGachaBadgeInfo.Add(new MenuGachaBadgeInfo()
+        {
+            DisplayStartDatetime = Google.Protobuf.WellKnownTypes.Timestamp.FromDateTimeOffset(DateTimeOffset.MinValue),
+            DisplayEndDatetime = Google.Protobuf.WellKnownTypes.Timestamp.FromDateTimeOffset(DateTimeOffset.MaxValue),
+        });
+
+        return Task.FromResult(response);
     }
 }
diff --git a/src/Services/GimmickService.cs b/src/Services/GimmickService.cs
index b2b3118..f8cf4c4 100644
--- a/src/Services/GimmickService.cs
+++ b/src/Services/GimmickService.cs
@@ -1,28 +1,144 @@
-using MariesWonderland.Proto.Gimmick;
 using Google.Protobuf.WellKnownTypes;
 using Grpc.Core;
+using MariesWonderland.Data;
+using MariesWonderland.Extensions;
+using MariesWonderland.Models.Entities;
+using MariesWonderland.Proto.Gimmick;
 
 namespace MariesWonderland.Services;
 
-public class GimmickService : MariesWonderland.Proto.Gimmick.GimmickService.GimmickServiceBase
+public class GimmickService(UserDataStore store) : MariesWonderland.Proto.Gimmick.GimmickService.GimmickServiceBase
 {
+    private readonly UserDataStore _store = store;
+
     public override Task<UpdateSequenceResponse> UpdateSequence(UpdateSequenceRequest request, ServerCallContext context)
     {
-        return Task.FromResult(new UpdateSequenceResponse());
+        long userId = context.GetUserId();
+        DarkUserMemoryDatabase userDb = _store.GetOrCreate(userId);
+        Dictionary<string, string> before = UserDataDiffBuilder.Snapshot(userDb);
+
+        // Ensure the sequence row exists so the client can track it
+        if (!userDb.EntityIUserGimmickSequence.Any(s =>
+            s.UserId == userId &&
+            s.GimmickSequenceScheduleId == request.GimmickSequenceScheduleId &&
+            s.GimmickSequenceId == request.GimmickSequenceId))
+        {
+            userDb.EntityIUserGimmickSequence.Add(new EntityIUserGimmickSequence
+            {
+                UserId = userId,
+                GimmickSequenceScheduleId = request.GimmickSequenceScheduleId,
+                GimmickSequenceId = request.GimmickSequenceId,
+            });
+        }
+
+        UpdateSequenceResponse response = new();
+        foreach (var (k, v) in UserDataDiffBuilder.Delta(before, userDb)) response.DiffUserData[k] = v;
+
+        return Task.FromResult(response);
     }
 
     public override Task<UpdateGimmickProgressResponse> UpdateGimmickProgress(UpdateGimmickProgressRequest request, ServerCallContext context)
     {
-        return Task.FromResult(new UpdateGimmickProgressResponse());
+        long userId = context.GetUserId();
+        DarkUserMemoryDatabase userDb = _store.GetOrCreate(userId);
+        Dictionary<string, string> before = UserDataDiffBuilder.Snapshot(userDb);
+
+        long nowMs = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
+
+        // Upsert the base gimmick progress row
+        EntityIUserGimmick? gimmick = userDb.EntityIUserGimmick.FirstOrDefault(g =>
+            g.UserId == userId &&
+            g.GimmickSequenceScheduleId == request.GimmickSequenceScheduleId &&
+            g.GimmickSequenceId == request.GimmickSequenceId &&
+            g.GimmickId == request.GimmickId);
+
+        if (gimmick == null)
+        {
+            gimmick = new EntityIUserGimmick
+            {
+                UserId = userId,
+                GimmickSequenceScheduleId = request.GimmickSequenceScheduleId,
+                GimmickSequenceId = request.GimmickSequenceId,
+                GimmickId = request.GimmickId,
+            };
+            userDb.EntityIUserGimmick.Add(gimmick);
+        }
+        gimmick.StartDatetime = nowMs;
+
+        // Upsert the ornament progress row, recording the progress bit from the client
+        EntityIUserGimmickOrnamentProgress? ornament = userDb.EntityIUserGimmickOrnamentProgress.FirstOrDefault(o =>
+            o.UserId == userId &&
+            o.GimmickSequenceScheduleId == request.GimmickSequenceScheduleId &&
+            o.GimmickSequenceId == request.GimmickSequenceId &&
+            o.GimmickId == request.GimmickId &&
+            o.GimmickOrnamentIndex == request.GimmickOrnamentIndex);
+
+        if (ornament == null)
+        {
+            ornament = new EntityIUserGimmickOrnamentProgress
+            {
+                UserId = userId,
+                GimmickSequenceScheduleId = request.GimmickSequenceScheduleId,
+                GimmickSequenceId = request.GimmickSequenceId,
+                GimmickId = request.GimmickId,
+                GimmickOrnamentIndex = request.GimmickOrnamentIndex,
+            };
+            userDb.EntityIUserGimmickOrnamentProgress.Add(ornament);
+        }
+        ornament.ProgressValueBit = request.ProgressValueBit;
+        ornament.BaseDatetime = nowMs;
+
+        UpdateGimmickProgressResponse response = new()
+        {
+            IsSequenceCleared = false,
+        };
+        foreach (var (k, v) in UserDataDiffBuilder.Delta(before, userDb)) response.DiffUserData[k] = v;
+
+        return Task.FromResult(response);
     }
 
     public override Task<InitSequenceScheduleResponse> InitSequenceSchedule(Empty request, ServerCallContext context)
     {
-        return Task.FromResult(new InitSequenceScheduleResponse());
+        long userId = context.GetUserId();
+        DarkUserMemoryDatabase userDb = _store.GetOrCreate(userId);
+        Dictionary<string, string> before = UserDataDiffBuilder.Snapshot(userDb);
+
+        // Read-only — returns all gimmick tables so the client can initialise its state
+        InitSequenceScheduleResponse response = new();
+        foreach (var (k, v) in UserDataDiffBuilder.Delta(before, userDb)) response.DiffUserData[k] = v;
+        return Task.FromResult(response);
     }
 
     public override Task<UnlockResponse> Unlock(UnlockRequest request, ServerCallContext context)
     {
-        return Task.FromResult(new UnlockResponse());
+        long userId = context.GetUserId();
+        DarkUserMemoryDatabase userDb = _store.GetOrCreate(userId);
+        Dictionary<string, string> before = UserDataDiffBuilder.Snapshot(userDb);
+
+        foreach (GimmickKey key in request.GimmickKey)
+        {
+            EntityIUserGimmickUnlock? unlock = userDb.EntityIUserGimmickUnlock.FirstOrDefault(u =>
+                u.UserId == userId &&
+                u.GimmickSequenceScheduleId == key.GimmickSequenceScheduleId &&
+                u.GimmickSequenceId == key.GimmickSequenceId &&
+                u.GimmickId == key.GimmickId);
+            if (unlock == null)
+            {
+                unlock = new EntityIUserGimmickUnlock
+                {
+                    UserId = userId,
+                    GimmickSequenceScheduleId = key.GimmickSequenceScheduleId,
+                    GimmickSequenceId = key.GimmickSequenceId,
+                    GimmickId = key.GimmickId,
+                };
+                userDb.EntityIUserGimmickUnlock.Add(unlock);
+            }
+            unlock.IsUnlocked = true;
+        }
+
+        UnlockResponse response = new();
+        foreach (var (k, v) in UserDataDiffBuilder.Delta(before, userDb)) response.DiffUserData[k] = v;
+
+        return Task.FromResult(response);
     }
 }
diff --git a/src/Services/IndividualPopService.cs b/src/Services/IndividualPopService.cs
index 22e457e..2285210 100644
--- a/src/Services/IndividualPopService.cs
+++ b/src/Services/IndividualPopService.cs
@@ -1,6 +1,6 @@
-using MariesWonderland.Proto.IndividualPop;
 using Google.Protobuf.WellKnownTypes;
 using Grpc.Core;
+using MariesWonderland.Proto.IndividualPop;
 
 namespace MariesWonderland.Services;
 
diff --git a/src/Services/NotificationService.cs b/src/Services/NotificationService.cs
index 11c71f6..fa51578 100644
--- a/src/Services/NotificationService.cs
+++ b/src/Services/NotificationService.cs
@@ -1,6 +1,6 @@
-using MariesWonderland.Proto.Notification;
 using Google.Protobuf.WellKnownTypes;
 using Grpc.Core;
+using MariesWonderland.Proto.Notification;
 
 namespace MariesWonderland.Services;
 
@@ -8,6 +8,11 @@ public class NotificationService : MariesWonderland.Proto.Notification.Notificat
 {
     public override Task<GetHeaderNotificationResponse> GetHeaderNotification(Empty request, ServerCallContext context)
     {
-        return Task.FromResult(new GetHeaderNotificationResponse());
+        return Task.FromResult(new GetHeaderNotificationResponse()
+        {
+            FriendRequestReceiveCount = 0,
+            GiftNotReceiveCount = 0,
+            IsExistUnreadInformation = false
+        });
     }
 }
diff --git a/src/Services/QuestService.cs b/src/Services/QuestService.cs
index 895fa72..9e81316 100644
--- a/src/Services/QuestService.cs
+++ b/src/Services/QuestService.cs
@@ -1,14 +1,66 @@
-using MariesWonderland.Proto.Quest;
 using Google.Protobuf.WellKnownTypes;
 using Grpc.Core;
+using MariesWonderland.Data;
+using MariesWonderland.Extensions;
+using MariesWonderland.Models.Entities;
+using MariesWonderland.Models.Type;
+using MariesWonderland.Proto.Quest;
 
 namespace MariesWonderland.Services;
 
-public class QuestService : MariesWonderland.Proto.Quest.QuestService.QuestServiceBase
+public class QuestService(UserDataStore store, DarkMasterMemoryDatabase masterDb, ILogger<QuestService> logger) : MariesWonderland.Proto.Quest.QuestService.QuestServiceBase
 {
+    private readonly UserDataStore _store = store;
+    private readonly DarkMasterMemoryDatabase _masterDb = masterDb;
+    private readonly ILogger<QuestService> _logger = logger;
+
     public override Task<UpdateMainFlowSceneProgressResponse> UpdateMainFlowSceneProgress(UpdateMainFlowSceneProgressRequest request, ServerCallContext context)
     {
-        return Task.FromResult(new UpdateMainFlowSceneProgressResponse());
+        long userId = context.GetUserId();
+        DarkUserMemoryDatabase userDb = _store.GetOrCreate(userId);
+        Dictionary<string, string> before = UserDataDiffBuilder.Snapshot(userDb);
+
+        int questSceneId = request.QuestSceneId;
+
+        // Resolve questId from the scene, then walk the master data chain to find the route:
+        // QuestScene -> MainQuestSequence (by QuestId) -> MainQuestSequenceGroup (by MainQuestSequenceId)
+        // -> MainQuestChapter (by MainQuestSequenceGroupId) -> MainQuestRouteId
+        EntityMQuestScene? scene = _masterDb.EntityMQuestScene.FirstOrDefault(s => s.QuestSceneId == questSceneId);
+        int routeId = 0;
+        if (scene != null)
+        {
+            EntityMMainQuestSequence? sequence = _masterDb.EntityMMainQuestSequence.FirstOrDefault(s => s.QuestId == scene.QuestId);
+            if (sequence != null)
+            {
+                EntityMMainQuestSequenceGroup? sequenceGroup = _masterDb.EntityMMainQuestSequenceGroup.FirstOrDefault(g => g.MainQuestSequenceId == sequence.MainQuestSequenceId);
+                if (sequenceGroup != null)
+                {
+                    EntityMMainQuestChapter? chapter = _masterDb.EntityMMainQuestChapter.FirstOrDefault(c => c.MainQuestSequenceGroupId == sequenceGroup.MainQuestSequenceGroupId);
+                    routeId = chapter?.MainQuestRouteId ?? 0;
+                }
+            }
+        }
+
+        EntityIUserMainQuestFlowStatus flowStatus = userDb.EntityIUserMainQuestFlowStatus.FirstOrDefault(s => s.UserId == userId)
+            ?? AddEntity(userDb.EntityIUserMainQuestFlowStatus, new EntityIUserMainQuestFlowStatus { UserId = userId });
+        flowStatus.CurrentQuestFlowType = QuestFlowType.MAIN_FLOW;
+
+        EntityIUserMainQuestMainFlowStatus mainFlowStatus = userDb.EntityIUserMainQuestMainFlowStatus.FirstOrDefault(s => s.UserId == userId)
+            ?? AddEntity(userDb.EntityIUserMainQuestMainFlowStatus, new EntityIUserMainQuestMainFlowStatus { UserId = userId });
+        mainFlowStatus.CurrentQuestSceneId = questSceneId;
+        mainFlowStatus.HeadQuestSceneId = Math.Max(mainFlowStatus.HeadQuestSceneId, questSceneId);
+        if (routeId != 0) mainFlowStatus.CurrentMainQuestRouteId = routeId;
+
+        UpdateMainFlowSceneProgressResponse response = new();
+        foreach (var (k, v) in UserDataDiffBuilder.Delta(before, userDb)) response.DiffUserData[k] = v;
+        return Task.FromResult(response);
+    }
+
+    /// <summary>Adds an entity to a list and returns it (convenience for inline new-entity seeding).</summary>
+    private static T AddEntity<T>(List<T> list, T entity)
+    {
+        list.Add(entity);
+        return entity;
     }
 
     public override Task<UpdateReplayFlowSceneProgressResponse> UpdateReplayFlowSceneProgress(UpdateReplayFlowSceneProgressRequest request, ServerCallContext context)
@@ -18,7 +70,57 @@ public class QuestService : MariesWonderland.Proto.Quest.QuestService.QuestServi
 
     public override Task<UpdateMainQuestSceneProgressResponse> UpdateMainQuestSceneProgress(UpdateMainQuestSceneProgressRequest request, ServerCallContext context)
     {
-        return Task.FromResult(new UpdateMainQuestSceneProgressResponse());
+        long userId = context.GetUserId();
+        DarkUserMemoryDatabase userDb = _store.GetOrCreate(userId);
+        Dictionary<string, string> before = UserDataDiffBuilder.Snapshot(userDb);
+
+        long nowMs = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
+        int questSceneId = request.QuestSceneId;
+
+        EntityMQuestScene? scene = _masterDb.EntityMQuestScene.FirstOrDefault(s => s.QuestSceneId == questSceneId);
+        EntityMQuest? quest = scene != null ? _masterDb.EntityMQuest.FirstOrDefault(q => q.QuestId == scene.QuestId) : null;
+
+        // IUserMainQuestMainFlowStatus — tracks current scene position and whether we've reached the last scene
+        EntityIUserMainQuestMainFlowStatus mainFlowStatus = userDb.EntityIUserMainQuestMainFlowStatus.FirstOrDefault(s => s.UserId == userId)
+            ?? AddEntity(userDb.EntityIUserMainQuestMainFlowStatus, new EntityIUserMainQuestMainFlowStatus { UserId = userId });
+        mainFlowStatus.CurrentQuestSceneId = questSceneId;
+        mainFlowStatus.HeadQuestSceneId = Math.Max(mainFlowStatus.HeadQuestSceneId, questSceneId);
+        if (scene?.QuestResultType is QuestResultType.HALF_RESULT or QuestResultType.FULL_RESULT)
+            mainFlowStatus.IsReachedLastQuestScene = true;
+
+        // IUserMainQuestFlowStatus and IUserMainQuestProgressStatus — sub-flow tracking for playable quests
+        bool isPlayable = quest != null && !quest.IsRunInTheBackground && quest.IsCountedAsQuest;
+        if (isPlayable)
+        {
+            EntityIUserMainQuestFlowStatus flowStatus = userDb.EntityIUserMainQuestFlowStatus.FirstOrDefault(s => s.UserId == userId)
+                ?? AddEntity(userDb.EntityIUserMainQuestFlowStatus, new EntityIUserMainQuestFlowStatus { UserId = userId });
+            flowStatus.CurrentQuestFlowType = QuestFlowType.SUB_FLOW;
+
+            EntityIUserMainQuestProgressStatus progressStatus = userDb.EntityIUserMainQuestProgressStatus.FirstOrDefault(s => s.UserId == userId)
+                ?? AddEntity(userDb.EntityIUserMainQuestProgressStatus, new EntityIUserMainQuestProgressStatus { UserId = userId });
+            progressStatus.CurrentQuestSceneId = questSceneId;
+            progressStatus.HeadQuestSceneId = Math.Max(progressStatus.HeadQuestSceneId, questSceneId);
+            progressStatus.CurrentQuestFlowType = QuestFlowType.SUB_FLOW;
+
+            // Reaching a result scene clears the quest; a full-result scene also increments clear counts
+            if (scene?.QuestResultType is QuestResultType.HALF_RESULT or QuestResultType.FULL_RESULT)
+            {
+                EntityIUserQuest userQuest = userDb.EntityIUserQuest.FirstOrDefault(q => q.UserId == userId && q.QuestId == quest!.QuestId)
+                    ?? AddEntity(userDb.EntityIUserQuest, new EntityIUserQuest { UserId = userId, QuestId = quest!.QuestId });
+                userQuest.QuestStateType = (int)QuestStateType.CLEARED;
+
+                if (scene.QuestResultType == QuestResultType.FULL_RESULT)
+                {
+                    userQuest.ClearCount++;
+                    userQuest.DailyClearCount++;
+                    userQuest.LastClearDatetime = nowMs;
+                }
+            }
+        }
+
+        UpdateMainQuestSceneProgressResponse response = new();
+        foreach (var (k, v) in UserDataDiffBuilder.Delta(before, userDb)) response.DiffUserData[k] = v;
+        return Task.FromResult(response);
     }
 
     public override Task<UpdateExtraQuestSceneProgressResponse> UpdateExtraQuestSceneProgress(UpdateExtraQuestSceneProgressRequest request, ServerCallContext context)
@@ -33,7 +135,62 @@ public class QuestService : MariesWonderland.Proto.Quest.QuestService.QuestServi
 
     public override Task<StartMainQuestResponse> StartMainQuest(StartMainQuestRequest request, ServerCallContext context)
     {
-        return Task.FromResult(new StartMainQuestResponse());
+        long userId = context.GetUserId();
+        DarkUserMemoryDatabase userDb = _store.GetOrCreate(userId);
+        Dictionary<string, string> before = UserDataDiffBuilder.Snapshot(userDb);
+
+        long nowMs = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
+        int questId = request.QuestId;
+
+        EntityMQuest? quest = _masterDb.EntityMQuest.FirstOrDefault(q => q.QuestId == questId);
+
+        // Ensure user quest and mission rows exist before any state transitions.
+        EntityIUserQuest userQuest = userDb.EntityIUserQuest.FirstOrDefault(q => q.UserId == userId && q.QuestId == questId)
+            ?? AddEntity(userDb.EntityIUserQuest, new EntityIUserQuest { UserId = userId, QuestId = questId });
+
+        if (quest != null && quest.QuestMissionGroupId != 0)
+        {
+            List<int> missionIds = [.. _masterDb.EntityMQuestMissionGroup
+                .Where(g => g.QuestMissionGroupId == quest.QuestMissionGroupId)
+                .Select(g => g.QuestMissionId)];
+
+            foreach (int missionId in missionIds)
+            {
+                if (!userDb.EntityIUserQuestMission.Any(m => m.UserId == userId && m.QuestId == questId && m.QuestMissionId == missionId))
+                    userDb.EntityIUserQuestMission.Add(new EntityIUserQuestMission { UserId = userId, QuestId = questId, QuestMissionId = missionId });
+            }
+        }
+
+        // Don't touch state on already-cleared quests (e.g. replaying a finished story quest).
+        if (userQuest.QuestStateType == (int)QuestStateType.CLEARED)
+        {
+            StartMainQuestResponse earlyResponse = new();
+            foreach (var (k, v) in UserDataDiffBuilder.Delta(before, userDb)) earlyResponse.DiffUserData[k] = v;
+            return Task.FromResult(earlyResponse);
+        }
+
+        userQuest.IsBattleOnly = request.IsBattleOnly;
+
+        // Background quests (cutscenes, non-combat) have no playable content — auto-clear them immediately.
+        // Playable quests transition to ACTIVE so the client knows a quest session is in progress.
+        bool isPlayable = quest != null && !quest.IsRunInTheBackground && quest.IsCountedAsQuest;
+        if (isPlayable)
+        {
+            userQuest.QuestStateType = (int)QuestStateType.ACTIVE;
+            userQuest.LatestStartDatetime = nowMs;
+        }
+        else
+        {
+            userQuest.QuestStateType = (int)QuestStateType.CLEARED;
+            userQuest.ClearCount++;
+            userQuest.DailyClearCount++;
+            userQuest.LastClearDatetime = nowMs;
+        }
+
+        StartMainQuestResponse response = new();
+        foreach (var (k, v) in UserDataDiffBuilder.Delta(before, userDb)) response.DiffUserData[k] = v;
+
+        return Task.FromResult(response);
     }
 
     public override Task<RestartMainQuestResponse> RestartMainQuest(RestartMainQuestRequest request, ServerCallContext context)
diff --git a/src/Services/TutorialService.cs b/src/Services/TutorialService.cs
index 143b5b6..7e92d57 100644
--- a/src/Services/TutorialService.cs
+++ b/src/Services/TutorialService.cs
@@ -1,17 +1,105 @@
-using MariesWonderland.Proto.Tutorial;
 using Grpc.Core;
+using MariesWonderland.Data;
+using MariesWonderland.Extensions;
+using MariesWonderland.Models.Entities;
+using MariesWonderland.Models.Type;
+using MariesWonderland.Proto.Tutorial;
 
 namespace MariesWonderland.Services;
 
-public class TutorialService : MariesWonderland.Proto.Tutorial.TutorialService.TutorialServiceBase
+public class TutorialService(UserDataStore store) : MariesWonderland.Proto.Tutorial.TutorialService.TutorialServiceBase
 {
     public override Task<SetTutorialProgressResponse> SetTutorialProgress(SetTutorialProgressRequest request, ServerCallContext context)
     {
-        return Task.FromResult(new SetTutorialProgressResponse());
+        long userId = context.GetUserId();
+        DarkUserMemoryDatabase userDb = store.GetOrCreate(userId);
+        Dictionary<string, string> before = UserDataDiffBuilder.Snapshot(userDb);
+
+        UpsertTutorialProgress(userDb, userId, (TutorialType)request.TutorialType, request.ProgressPhase, request.ChoiceId);
+
+        SetTutorialProgressResponse response = new();
+        foreach ((string k, Proto.Data.DiffData v) in UserDataDiffBuilder.Delta(before, userDb))
+            response.DiffUserData[k] = v;
+
+        return Task.FromResult(response);
     }
 
     public override Task<SetTutorialProgressAndReplaceDeckResponse> SetTutorialProgressAndReplaceDeck(SetTutorialProgressAndReplaceDeckRequest request, ServerCallContext context)
     {
-        return Task.FromResult(new SetTutorialProgressAndReplaceDeckResponse());
+        long userId = context.GetUserId();
+        DarkUserMemoryDatabase userDb = store.GetOrCreate(userId);
+        Dictionary<string, string> before = UserDataDiffBuilder.Snapshot(userDb);
+
+        UpsertTutorialProgress(userDb, userId, (TutorialType)request.TutorialType, request.ProgressPhase, choiceId: 0);
+        UpsertDeck(userDb, userId, request);
+
+        SetTutorialProgressAndReplaceDeckResponse response = new();
+        foreach ((string k, Proto.Data.DiffData v) in UserDataDiffBuilder.Delta(before, userDb))
+            response.DiffUserData[k] = v;
+
+        return Task.FromResult(response);
+    }
+
+    private static void UpsertTutorialProgress(DarkUserMemoryDatabase db, long userId, TutorialType type, int phase, int choiceId)
+    {
+        EntityIUserTutorialProgress? existing = db.EntityIUserTutorialProgress
+            .FirstOrDefault(t => t.UserId == userId && t.TutorialType == type);
+
+        if (existing is null)
+        {
+            db.EntityIUserTutorialProgress.Add(new EntityIUserTutorialProgress
+            {
+                UserId = userId,
+                TutorialType = type,
+                ProgressPhase = phase,
+                ChoiceId = choiceId
+            });
+        }
+        else
+        {
+            existing.ProgressPhase = phase;
+            existing.ChoiceId = choiceId;
+        }
+    }
+
+    /// <summary>
+    /// Upserts the user's deck from a SetTutorialProgressAndReplaceDeck request.
+    /// During tutorial the client sends the deck it wants to play with — we record the
+    /// costume UUIDs from each slot and seed sensible defaults for name and power.
+    /// </summary>
+    private static void UpsertDeck(DarkUserMemoryDatabase db, long userId, SetTutorialProgressAndReplaceDeckRequest request)
+    {
+        DeckType deckType = (DeckType)request.DeckType;
+        long now = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
+
+        string uuid01 = request.Deck?.Character01?.UserCostumeUuid ?? "";
+        string uuid02 = request.Deck?.Character02?.UserCostumeUuid ?? "";
+        string uuid03 = request.Deck?.Character03?.UserCostumeUuid ?? "";
+
+        EntityIUserDeck? existing = db.EntityIUserDeck
+            .FirstOrDefault(d => d.UserId == userId && d.DeckType == deckType && d.UserDeckNumber == request.UserDeckNumber);
+
+        if (existing is null)
+        {
+            db.EntityIUserDeck.Add(new EntityIUserDeck(
+                UserId: userId,
+                DeckType: deckType,
+                UserDeckNumber: request.UserDeckNumber,
+                UserDeckCharacterUuid01: uuid01,
+                UserDeckCharacterUuid02: uuid02,
+                UserDeckCharacterUuid03: uuid03,
+                Name: "Deck 1",
+                Power: 100,
+                LatestVersion: now
+            ));
+        }
+        else
+        {
+            if (!string.IsNullOrEmpty(uuid01)) existing.UserDeckCharacterUuid01 = uuid01;
+            if (!string.IsNullOrEmpty(uuid02)) existing.UserDeckCharacterUuid02 = uuid02;
+            if (!string.IsNullOrEmpty(uuid03)) existing.UserDeckCharacterUuid03 = uuid03;
+            existing.LatestVersion = now;
+        }
     }
 }
+
diff --git a/src/Services/UserService.cs b/src/Services/UserService.cs
index 3033962..1d753f5 100644
--- a/src/Services/UserService.cs
+++ b/src/Services/UserService.cs
@@ -65,7 +65,18 @@ public class UserService(UserDataStore store) : MariesWonderland.Proto.User.User
 
     public override Task<GameStartResponse> GameStart(Empty request, ServerCallContext context)
     {
-        return Task.FromResult(new GameStartResponse());
+        long userId = context.GetUserId();
+        DarkUserMemoryDatabase userDb = _store.GetOrCreate(userId);
+
+        Dictionary<string, string> before = UserDataDiffBuilder.Snapshot(userDb);
+
+        EntityIUser user = userDb.EntityIUser.FirstOrDefault(u => u.UserId == userId)
+            ?? AddEntity(userDb.EntityIUser, new EntityIUser { UserId = userId });
+        user.GameStartDatetime = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
+
+        GameStartResponse response = new();
+        foreach (var (k, v) in UserDataDiffBuilder.Delta(before, userDb)) response.DiffUserData[k] = v;
+        return Task.FromResult(response);
     }
 
     public override Task<GetBackupTokenResponse> GetBackupToken(GetBackupTokenRequest request, ServerCallContext context)
diff --git a/src/appsettings.Development.json b/src/appsettings.Development.json
index cadd9ab..100819a 100644
--- a/src/appsettings.Development.json
+++ b/src/appsettings.Development.json
@@ -14,7 +14,8 @@
     "Data": {
       "LatestMasterDataVersion": "20240404193219",
       "UserDataPath": "Data/UserData",
-      "MasterDataPath": "Data/MasterData"
+      "MasterDataPath": "Data/MasterData",
+      "UserDatabase": "userdata.json"
     }
   }
 }
diff --git a/src/appsettings.json b/src/appsettings.json
index a318bbf..dfe0ab0 100644
--- a/src/appsettings.json
+++ b/src/appsettings.json
@@ -22,7 +22,8 @@
     "Data": {
       "LatestMasterDataVersion": "",
       "UserDataPath": "",
-      "MasterDataPath": ""
+      "MasterDataPath": "",
+      "UserDatabase": "userdata.json"
     }
   }
 }