diff --git a/apps/client/src/manifest.ts b/apps/client/src/manifest.ts
index 203c068..0970435 100644
--- a/apps/client/src/manifest.ts
+++ b/apps/client/src/manifest.ts
@@ -2,15 +2,30 @@ import { updateFiles } from "./files";
 import { MANIFEST } from "./server";
 
 export const updateManifest = async (dir: string) => {
-  MANIFEST.version = await getVersion();
   MANIFEST.files = [];
   await updateFiles(dir);
+  MANIFEST.version = await getVersion(dir);
 };
 
-const getVersion = async () => {
+const getVersion = async (dir: string) => {
   try {
     return await Bun.file("public/version").text();
   } catch {
-    return "0.0.0";
+    return await fingerprintFiles(dir);
   }
 };
+
+const fingerprintFiles = async (dir: string): Promise<string> => {
+  const stamps = await Promise.all(
+    MANIFEST.files.map(async ({ path }) => {
+      try {
+        const stat = await Bun.file(`${dir}${path}`).stat();
+        return `${path}:${stat.size}:${stat.mtimeMs}`;
+      } catch {
+        return `${path}:missing`;
+      }
+    }),
+  );
+  stamps.sort();
+  return Bun.hash(stamps.join("|")).toString(16);
+};
diff --git a/apps/website/src/cache/cache.ts b/apps/website/src/cache/cache.ts
index f5d0236..969dbeb 100644
--- a/apps/website/src/cache/cache.ts
+++ b/apps/website/src/cache/cache.ts
@@ -10,18 +10,41 @@ import { Logger } from "../utils/logger.utils";
 import { setVersion } from "../version";
 import { setLoadingStatus, setLoadingTotalFiles } from "../window";
 
+const CACHE_LOCK_NAME = "nanoforge-game-cache";
+
+async function withCacheLock<T>(fn: () => Promise<T>): Promise<T> {
+  if (typeof navigator === "undefined" || !navigator.locks) return fn();
+  return await navigator.locks.request(CACHE_LOCK_NAME, fn);
+}
+
 export class GameCache {
   private readonly logger: Logger = new Logger("Cache");
   private readonly fs: FileSystemManager = new FileSystemManager("game");
 
   async updateCache(manifest: IManifest, force = false): Promise<IExtendedManifest> {
     this.logger.info("Starting cache game files");
-    let extendedManifest: IExtendedManifest | undefined = await this._parseCache(manifest);
-    if (force || !isManifestUpToDate(manifest) || !extendedManifest)
-      extendedManifest = await this._updateCacheProcess(manifest);
+
+    let extendedManifest = await this._tryReuseCache(manifest, force);
+
+    if (!extendedManifest) {
+      extendedManifest = await withCacheLock(async () => {
+        return (
+          (await this._tryReuseCache(manifest, force)) ?? (await this._updateCacheProcess(manifest))
+        );
+      });
+    }
+
     setVersion(manifest.version);
     this.logger.info("Game files cached");
-    return extendedManifest as IExtendedManifest;
+    return extendedManifest;
+  }
+
+  private async _tryReuseCache(
+    manifest: IManifest,
+    force: boolean,
+  ): Promise<IExtendedManifest | undefined> {
+    if (force || !isManifestUpToDate(manifest)) return undefined;
+    return this._parseCache(manifest);
   }
 
   private async _updateCacheProcess(manifest: IManifest): Promise<IExtendedManifest> {
diff --git a/apps/website/src/index.ts b/apps/website/src/index.ts
index 991b999..f5a58e3 100644
--- a/apps/website/src/index.ts
+++ b/apps/website/src/index.ts
@@ -20,7 +20,7 @@ const runLoad = async () => {
   const manifest = await getManifest();
   runWatcher(manifest.watch);
   const cache = new GameCache();
-  const extendedManifest = await cache.updateCache(manifest, true);
+  const extendedManifest = await cache.updateCache(manifest);
   const [files, mainModule] = await loadGameFiles(extendedManifest);
   const env = await getEnv();
   setLoadingStatus("Starting game");
diff --git a/apps/website/src/manifest.ts b/apps/website/src/manifest.ts
index 8fa739c..9c3931a 100644
--- a/apps/website/src/manifest.ts
+++ b/apps/website/src/manifest.ts
@@ -15,5 +15,5 @@ export const isManifestUpToDate = (manifest: IManifest): boolean => {
   setLoadingStatus("Verifying manifest");
   const currentVersion = getVersion();
   if (!currentVersion || currentVersion !== manifest.version) return false;
-  return false;
+  return true;
 };