diff --git a/src/client/JoinPrivateLobbyModal.ts b/src/client/JoinPrivateLobbyModal.ts
index 4f4aa2989..ccedb0bd1 100644
--- a/src/client/JoinPrivateLobbyModal.ts
+++ b/src/client/JoinPrivateLobbyModal.ts
@@ -8,7 +8,7 @@ import {
 } from "../core/WorkerSchemas";
 import { customElement, query, state } from "lit/decorators.js";
 import { JoinLobbyEvent } from "./Main";
-import { generateID } from "../core/Util";
+import { getClientID } from "../core/Util";
 import { getServerConfigFromClient } from "../core/configuration/ConfigLoader";
 import { translateText } from "../client/Utils";
 
@@ -220,7 +220,7 @@ export class JoinPrivateLobbyModal extends LitElement {
         new CustomEvent("join-lobby", {
           detail: {
             gameID: lobbyId,
-            clientID: generateID(),
+            clientID: getClientID(lobbyId),
           } as JoinLobbyEvent,
           bubbles: true,
           composed: true,
@@ -265,7 +265,7 @@ export class JoinPrivateLobbyModal extends LitElement {
           detail: {
             gameID: lobbyId,
             gameRecord: archiveData.gameRecord,
-            clientID: generateID(),
+            clientID: getClientID(lobbyId),
           } as JoinLobbyEvent,
           bubbles: true,
           composed: true,
diff --git a/src/client/LocalPersistantStats.ts b/src/client/LocalPersistantStats.ts
index e060a8b91..051a3a9d7 100644
--- a/src/client/LocalPersistantStats.ts
+++ b/src/client/LocalPersistantStats.ts
@@ -4,8 +4,8 @@ import {
   GameID,
   GameRecord,
   GameRecordSchema,
-  ID,
 } from "../core/Schemas";
+import { ID } from "../core/BaseSchemas";
 import { replacer } from "../core/Util";
 import { z } from "zod";
 
diff --git a/src/client/Main.ts b/src/client/Main.ts
index 1378d20e8..b5bcd23d2 100644
--- a/src/client/Main.ts
+++ b/src/client/Main.ts
@@ -8,7 +8,7 @@ import "./components/NewsButton";
 import "./components/baseComponents/Button";
 import "./components/baseComponents/Modal";
 import "./styles.css";
-import { GameRecord, GameStartInfo, ID } from "../core/Schemas";
+import { GameRecord, GameStartInfo } from "../core/Schemas";
 import { discordLogin, getUserMe, isLoggedIn, logOut } from "./jwt";
 import { generateCryptoRandomUUID, incrementGamesPlayed, translateText } from "./Utils";
 import { DarkModeButton } from "./DarkModeButton";
@@ -19,6 +19,7 @@ import { GameStartingModal } from "./GameStartingModal";
 import { GameType } from "../core/game/Game";
 import { HelpModal } from "./HelpModal";
 import { HostLobbyModal } from "./HostLobbyModal";
+import { ID } from "../core/BaseSchemas";
 import { JoinPrivateLobbyModal } from "./JoinPrivateLobbyModal";
 import { LangSelector } from "./LangSelector";
 import { LanguageModal } from "./LanguageModal";
@@ -34,6 +35,7 @@ import { UserMeResponse } from "../core/ApiSchemas";
 import { UserSettingModal } from "./UserSettingModal";
 import { UserSettings } from "../core/game/UserSettings";
 import { UsernameInput } from "./UsernameInput";
+import { getClientID } from "../core/Util";
 import { getServerConfigFromClient } from "../core/configuration/ConfigLoader";
 import { joinLobby } from "./ClientGameRunner";
 import version from "../../resources/version.txt";
@@ -474,7 +476,7 @@ class Client {
             : this.flagInput.getCurrentFlag(),
         playerName: this.usernameInput?.getCurrentUsername() ?? "",
         token: getPlayToken(),
-        clientID: lobby.clientID,
+        clientID: getClientID(lobby.gameID),
         gameStartInfo: lobby.gameStartInfo ?? lobby.gameRecord?.info,
         gameRecord: lobby.gameRecord,
       },
diff --git a/src/client/PublicLobby.ts b/src/client/PublicLobby.ts
index c194d0c2e..cd98d36b9 100644
--- a/src/client/PublicLobby.ts
+++ b/src/client/PublicLobby.ts
@@ -4,7 +4,7 @@ import { LitElement, html } from "lit";
 import { customElement, state } from "lit/decorators.js";
 import { ApiPublicLobbiesResponseSchema } from "../core/ExpressSchemas";
 import { JoinLobbyEvent } from "./Main";
-import { generateID } from "../core/Util";
+import { getClientID } from "../core/Util";
 import { terrainMapFileLoader } from "./TerrainMapFileLoader";
 import { translateText } from "../client/Utils";
 
@@ -205,7 +205,7 @@ export class PublicLobby extends LitElement {
         new CustomEvent("join-lobby", {
           detail: {
             gameID: lobby.gameID,
-            clientID: generateID(),
+            clientID: getClientID(lobby.gameID),
           } as JoinLobbyEvent,
           bubbles: true,
           composed: true,
diff --git a/src/client/SinglePlayerModal.ts b/src/client/SinglePlayerModal.ts
index 7d6497474..577a9257f 100644
--- a/src/client/SinglePlayerModal.ts
+++ b/src/client/SinglePlayerModal.ts
@@ -15,13 +15,13 @@ import {
 } from "../core/game/Game";
 import { LitElement, html } from "lit";
 import { customElement, query, state } from "lit/decorators.js";
+import { generateID, getClientID } from "../core/Util";
 import { DifficultyDescription } from "./components/Difficulties";
 import { FlagInput } from "./FlagInput";
 import { JoinLobbyEvent } from "./Main";
 import { TeamCountConfig } from "../core/Schemas";
 import { UserSettings } from "../core/game/UserSettings";
 import { UsernameInput } from "./UsernameInput";
-import { generateID } from "../core/Util";
 import randomMap from "../../resources/images/RandomMap.webp";
 import { renderUnitTypeOptions } from "./utilities/RenderUnitTypeOptions";
 import { translateText } from "../client/Utils";
@@ -413,8 +413,8 @@ export class SinglePlayerModal extends LitElement {
       `Starting single player game with map: ${GameMapType[this.selectedMap as keyof typeof GameMapType]
       }${this.useRandomMap ? " (Randomly selected)" : ""}`,
     );
-    const clientID = generateID();
     const gameID = generateID();
+    const clientID = getClientID(gameID);
 
     const usernameInput = document.querySelector(
       "username-input",
diff --git a/src/core/BaseSchemas.ts b/src/core/BaseSchemas.ts
new file mode 100644
index 000000000..86f6b09d7
--- /dev/null
+++ b/src/core/BaseSchemas.ts
@@ -0,0 +1,7 @@
+// This file contains shared schemas
+import { z } from "zod";
+
+export const ID = z
+  .string()
+  .regex(/^[a-zA-Z0-9]+$/)
+  .length(8);
diff --git a/src/core/Schemas.ts b/src/core/Schemas.ts
index b4a06bd2e..e70b9c960 100644
--- a/src/core/Schemas.ts
+++ b/src/core/Schemas.ts
@@ -10,6 +10,7 @@ import {
   Trios,
   UnitType,
 } from "./game/Game";
+import { ID } from "./BaseSchemas";
 import { PatternDecoder } from "./PatternDecoder";
 import { PlayerStatsSchema } from "./StatsSchemas";
 import { base64url } from "jose";
@@ -176,10 +177,6 @@ const EmojiSchema = z
   .number()
   .nonnegative()
   .max(flattenedEmojiTable.length - 1);
-export const ID = z
-  .string()
-  .regex(/^[a-zA-Z0-9]+$/)
-  .length(8);
 
 export const AllPlayersStatsSchema = z.record(ID, PlayerStatsSchema);
 
diff --git a/src/core/Util.ts b/src/core/Util.ts
index 8a35a43f1..cb919dd72 100644
--- a/src/core/Util.ts
+++ b/src/core/Util.ts
@@ -4,6 +4,7 @@ import {
 } from "./execution/utils/BotNames";
 import { Cell, Unit } from "./game/Game";
 import {
+  ClientID,
   GameConfig,
   GameID,
   GameRecord,
@@ -13,6 +14,7 @@ import {
 } from "./Schemas";
 import { GameMap, TileRef } from "./game/GameMap";
 import DOMPurify from "dompurify";
+import { ID } from "./BaseSchemas";
 import { ServerConfig } from "./configuration/Config";
 import { customAlphabet } from "nanoid";
 
@@ -227,6 +229,19 @@ export function generateID(): GameID {
   return nanoid();
 }
 
+export function getClientID(gameID: GameID): ClientID {
+  const cachedGame = localStorage.getItem("game_id");
+  const cachedClient = localStorage.getItem("client_id");
+
+  if (gameID === cachedGame && cachedClient && ID.safeParse(cachedClient).success) return cachedClient;
+
+  const clientId = generateID();
+  localStorage.setItem("game_id", gameID);
+  localStorage.setItem("client_id", clientId);
+
+  return clientId;
+}
+
 export function toInt(num: number): bigint {
   if (num === Infinity) {
     return BigInt(Number.MAX_SAFE_INTEGER);
diff --git a/src/server/Master.ts b/src/server/Master.ts
index 7c860b355..b33ac5241 100644
--- a/src/server/Master.ts
+++ b/src/server/Master.ts
@@ -1,7 +1,8 @@
 /* eslint-disable @typescript-eslint/no-unsafe-member-access */
 import { ApiEnvResponse, ApiPublicLobbiesResponse } from "../core/ExpressSchemas";
-import { GameInfo, ID } from "../core/Schemas";
 import { LimiterType, gatekeeper } from "./Gatekeeper";
+import { GameInfo } from "../core/Schemas";
+import { ID } from "../core/BaseSchemas";
 import { MapPlaylist } from "./MapPlaylist";
 import cluster from "cluster";
 import express from "express";
diff --git a/src/server/Worker.ts b/src/server/Worker.ts
index 43ffe9d7f..202dd184a 100644
--- a/src/server/Worker.ts
+++ b/src/server/Worker.ts
@@ -3,7 +3,7 @@ import {
   GameInputSchema,
   WorkerApiGameIdExists,
 } from "../core/WorkerSchemas";
-import { GameRecord, GameRecordSchema, ID } from "../core/Schemas";
+import { GameRecord, GameRecordSchema } from "../core/Schemas";
 import { LimiterType, gatekeeper } from "./Gatekeeper";
 import { WebSocket, WebSocketServer } from "ws";
 import { archive, readGameRecord } from "./Archive";
@@ -11,6 +11,7 @@ import express, { NextFunction, Request, Response } from "express";
 import { GameEnv } from "../core/configuration/Config";
 import { GameManager } from "./GameManager";
 import { GameType } from "../core/game/Game";
+import { ID } from "../core/BaseSchemas";
 import { PrivilegeRefresher } from "./PrivilegeRefresher";
 import { fileURLToPath } from "url";
 import { getServerConfigFromServer } from "../core/configuration/ConfigLoader";
diff --git a/tests/core/Util.test.ts b/tests/core/Util.test.ts
new file mode 100644
index 000000000..a2028ce83
--- /dev/null
+++ b/tests/core/Util.test.ts
@@ -0,0 +1,55 @@
+import { getClientID } from "../../src/core/Util";
+
+describe("Util", () => {
+  class InMemoryLocalStorage {
+    private readonly store = new Map<string, string>();
+    getItem(key: string): string | null {
+      return this.store.has(key) ? this.store.get(key)! : null;
+    }
+    setItem(key: string, value: string): void {
+      this.store.set(key, String(value));
+    }
+    removeItem(key: string): void {
+      this.store.delete(key);
+    }
+    clear(): void {
+      this.store.clear();
+    }
+  }
+
+  beforeEach(() => {
+    (globalThis as any).localStorage = new InMemoryLocalStorage();
+  });
+
+  test("creates and persists a new client", () => {
+    expect((globalThis as any).localStorage.getItem("client_id")).toBeNull();
+
+    const id = getClientID("testGameID");
+
+    expect(typeof id).toBe("string");
+    expect(id).toMatch(/^[0-9a-zA-Z]{8}$/);
+
+    const stored = (globalThis as any).localStorage.getItem("client_id");
+    expect(stored).toBe(id);
+  });
+
+  test("creates two games and make sure only last one is updated", () => {
+    const id1 = getClientID("testGameID1");
+    const id2 = getClientID("testGameID2");
+
+    expect(id1).not.toBe(id2);
+
+    const stored = (globalThis as any).localStorage.getItem("client_id");
+    expect(stored).toBe(id2);
+  });
+
+  test("creates two games with same game id, make sure the id stays the same", () => {
+    const id1 = getClientID("testGameID1");
+    const id2 = getClientID("testGameID1");
+
+    expect(id1).toBe(id2);
+
+    const stored = (globalThis as any).localStorage.getItem("client_id");
+    expect(stored).toBe(id1);
+  });
+});