diff --git a/frontend/app/lib/hooks/useUserMode.ts b/frontend/app/lib/hooks/useUserMode.ts
new file mode 100644
index 00000000..91fc2d3a
--- /dev/null
+++ b/frontend/app/lib/hooks/useUserMode.ts
@@ -0,0 +1,22 @@
+import { useCallback } from "react";
+import { usePathname, useRouter, useSearchParams } from "next/navigation";
+
+export type UserModeType = "viewer" | "player";
+
+export function useUserMode(): [UserModeType, (mode: UserModeType) => void] {
+  const pathname = usePathname();
+  const { replace } = useRouter();
+  const searchParams = useSearchParams();
+  const userMode = searchParams.get("mode") == "player" ? "player" : "viewer";
+
+  const setUserMode = useCallback(
+    (mode: UserModeType) => {
+      const params = new URLSearchParams(searchParams);
+      params.set("mode", mode);
+      replace(`${pathname}?${params.toString()}`);
+    },
+    [searchParams, pathname, replace],
+  );
+
+  return [userMode, setUserMode];
+}
diff --git a/frontend/app/pong/[id]/PongBoard.tsx b/frontend/app/pong/[id]/PongBoard.tsx
index 60c1f7f8..d3e3d002 100644
--- a/frontend/app/pong/[id]/PongBoard.tsx
+++ b/frontend/app/pong/[id]/PongBoard.tsx
@@ -8,7 +8,7 @@ import { io } from "socket.io-client";
 import type { Socket } from "socket.io-client";
 import PongInformationBoard from "./PongInformationBoard";
 import { useTheme } from "next-themes";
-import { useSearchParams } from "next/navigation";
+import { useUserMode } from "@/app/lib/hooks/useUserMode";
 
 type setState<T> = T | ((prevState: T) => T);
 
@@ -34,12 +34,13 @@ interface HandleActionProps {
 
 const POINT_TO_WIN = 3;
 
-function PongBoard({ id: id }: PongBoardProps) {
+function PongBoard({ id }: PongBoardProps) {
   const [fps, setFps] = useStateCallback<number>(0);
   const [speed, setSpeed] = useStateCallback<number>(0);
   const [player1Position, setPlayer1Position] = useStateCallback<number>(0);
   const [player2Position, setPlayer2Position] = useStateCallback<number>(0);
   const [logs, setLogs] = useStateCallback<string[]>([]);
+  const [userMode, setUserMode] = useUserMode();
 
   const canvasRef = useRef<HTMLCanvasElement | null>(null); // only initialized once
   const gameRef = useRef<PongGame | null>(null); // only initialized once
@@ -49,8 +50,6 @@ function PongBoard({ id: id }: PongBoardProps) {
   const [battleDisabled] = useState(true);
   const { resolvedTheme } = useTheme();
   const defaultColor = "hsl(0, 0%, 0%)";
-  const searchParams = useSearchParams();
-  const isPlayer = searchParams.get("mode") == "player";
 
   const getGame = useCallback(() => {
     const ctx = canvasRef.current?.getContext("2d");
@@ -66,16 +65,16 @@ function PongBoard({ id: id }: PongBoardProps) {
         setPlayer2Position,
         defaultColor,
         defaultColor,
-        isPlayer,
+        userMode,
       );
       gameRef.current = game;
       return game;
     }
     return gameRef.current;
-  }, [setFps, setSpeed, setPlayer1Position, setPlayer2Position, isPlayer]);
+  }, [setFps, setSpeed, setPlayer1Position, setPlayer2Position, userMode]);
 
   const start = useCallback(() => {
-    if (!isPlayer) return;
+    if (!userMode) return;
     const game = getGame();
 
     setStartDisabled(true);
@@ -85,7 +84,12 @@ function PongBoard({ id: id }: PongBoardProps) {
       vx: -vx,
       vy: -vy,
     });
-  }, [getGame, isPlayer]);
+  }, [getGame, userMode]);
+
+  useEffect(() => {
+    const game = getGame();
+    game.setUserMode(userMode);
+  }, [getGame, userMode]);
 
   useEffect(() => {
     // TODO: Use --foreground color from CSS
@@ -130,7 +134,9 @@ function PongBoard({ id: id }: PongBoardProps) {
   }, [getGame]);
 
   useEffect(() => {
-    const socket = io("/pong", { query: { game_id: id, is_player: isPlayer } });
+    const socket = io("/pong", {
+      query: { game_id: id, is_player: userMode === "player" },
+    });
     socketRef.current = socket;
 
     const game = getGame();
@@ -139,6 +145,10 @@ function PongBoard({ id: id }: PongBoardProps) {
     };
 
     const handleLog = (log: string) => {
+      // TODO
+      if (log == "The game is full. You joined as a viewer.") {
+        setUserMode("viewer");
+      }
       setLogs((logs) => [...logs, log]);
     };
     const handleConnect = () => {
@@ -154,7 +164,7 @@ function PongBoard({ id: id }: PongBoardProps) {
     };
 
     const handleRight = ({ playerNumber }: HandleActionProps) => {
-      if (!isPlayer && playerNumber == 1) {
+      if (userMode !== "player" && playerNumber == 1) {
         game.movePlayer1Left();
       } else {
         game.movePlayer2Left();
@@ -162,7 +172,7 @@ function PongBoard({ id: id }: PongBoardProps) {
     };
 
     const handleLeft = ({ playerNumber }: HandleActionProps) => {
-      if (!isPlayer && playerNumber == 1) {
+      if (userMode !== "player" && playerNumber == 1) {
         game.movePlayer1Right();
       } else {
         game.movePlayer2Right();
@@ -170,7 +180,7 @@ function PongBoard({ id: id }: PongBoardProps) {
     };
 
     const handleBounce = ({ playerNumber }: HandleActionProps) => {
-      if (!isPlayer && playerNumber == 1) {
+      if (userMode !== "player" && playerNumber == 1) {
         game.bounceOffPaddlePlayer1();
       } else {
         game.bounceOffPaddlePlayer2();
@@ -180,7 +190,7 @@ function PongBoard({ id: id }: PongBoardProps) {
     const handleCollide = (msg: HandleActionProps) => {
       const { playerNumber } = msg;
       console.log(msg);
-      if (isPlayer) {
+      if (userMode === "player") {
         const score = game.increaseScorePlayer1();
         if (score != POINT_TO_WIN) {
           setTimeout(() => start(), 1000);
@@ -241,7 +251,7 @@ function PongBoard({ id: id }: PongBoardProps) {
       socket.off("finish", handleFinish);
       socket.disconnect();
     };
-  }, [id, getGame, setLogs, start, isPlayer]);
+  }, [id, getGame, setLogs, start, userMode, setUserMode]);
 
   return (
     <div className="overflow-hidden flex-grow flex gap-8 pb-8">
@@ -275,7 +285,7 @@ function PongBoard({ id: id }: PongBoardProps) {
           player1Position={player1Position}
           player2Position={player2Position}
           logs={logs}
-          isPlayer={isPlayer}
+          userMode={userMode}
         />
       </div>
     </div>
diff --git a/frontend/app/pong/[id]/PongGame.ts b/frontend/app/pong/[id]/PongGame.ts
index 1f21b3f4..05110032 100644
--- a/frontend/app/pong/[id]/PongGame.ts
+++ b/frontend/app/pong/[id]/PongGame.ts
@@ -13,6 +13,7 @@ import {
 type setFunction<T> = (value: T | ((prevState: T) => T)) => void;
 type movingDirectionType = "none" | "left" | "right";
 type onActionType = (action: string) => void;
+type userModeType = "player" | "viewer";
 
 export class PongGame {
   private ctx: CanvasRenderingContext2D;
@@ -34,7 +35,7 @@ export class PongGame {
   onAction: onActionType | undefined;
   private paddleColor: string;
   private ballColor: string;
-  private isPlayer: boolean;
+  private userMode: userModeType;
 
   constructor(
     ctx: CanvasRenderingContext2D,
@@ -44,7 +45,7 @@ export class PongGame {
     setPlayer2Position: setFunction<number>,
     paddleColor: string,
     ballColor: string,
-    isPlayer: boolean,
+    userMode: userModeType,
   ) {
     this.ctx = ctx;
     this.ctx.textAlign = "center";
@@ -78,7 +79,7 @@ export class PongGame {
     this.setSpeed = setSpeed;
     this.setPlayer1Position = setPlayer1Position;
     this.setPlayer2Position = setPlayer2Position;
-    this.isPlayer = isPlayer;
+    this.userMode = userMode;
   }
 
   update_fps = () => {
@@ -113,12 +114,12 @@ export class PongGame {
     // Draw objects
     this.ball.move(this.elapsed);
     if (this.player1.collide_with(this.ball)) {
-      if (this.isPlayer) {
+      if (this.userMode === "player") {
         this.ball.bounce_off_paddle(this.player1);
         this.onAction && this.onAction("bounce");
       }
     } else if (this.ball.y + this.ball.radius * 2 >= CANVAS_HEIGHT) {
-      if (this.isPlayer) {
+      if (this.userMode === "player") {
         this.ball.reset();
         this.score.player2++;
         this.onAction && this.onAction("collide");
@@ -148,7 +149,7 @@ export class PongGame {
     this.update_fps();
     this.update_speed(this.ball.speed());
     this.update_players();
-    if (this.isPlayer) {
+    if (this.userMode === "player") {
       if (this.movingDirection === "left") {
         this.player1.clear(this.ctx);
         this.player1.move_left();
@@ -300,4 +301,8 @@ export class PongGame {
     this.player1.color = color;
     this.player2.color = color;
   }
+
+  setUserMode(userMode: userModeType) {
+    this.userMode = userMode;
+  }
 }
diff --git a/frontend/app/pong/[id]/PongInformationBoard.tsx b/frontend/app/pong/[id]/PongInformationBoard.tsx
index 6d53a5a3..5d306949 100644
--- a/frontend/app/pong/[id]/PongInformationBoard.tsx
+++ b/frontend/app/pong/[id]/PongInformationBoard.tsx
@@ -6,7 +6,7 @@ interface PongInformationBoardProps {
   player1Position: number;
   player2Position: number;
   logs: string[];
-  isPlayer: boolean;
+  userMode: "viewer" | "player";
 }
 
 export default function PongInformationBoard({
@@ -15,11 +15,11 @@ export default function PongInformationBoard({
   player1Position,
   player2Position,
   logs,
-  isPlayer,
+  userMode,
 }: PongInformationBoardProps) {
   return (
     <div className="overflow-hidden flex-grow flex flex-col gap-1">
-      <div>You are a {isPlayer ? "player" : "viewer"}</div>
+      <div>You are a {userMode}</div>
       <div id="fps">FPS: {fps}</div>
       <div id="speed">Speed: {speed}</div>
       <div>
diff --git a/frontend/app/pong/[id]/page.tsx b/frontend/app/pong/[id]/page.tsx
index 1ceeedb1..580ed6ef 100644
--- a/frontend/app/pong/[id]/page.tsx
+++ b/frontend/app/pong/[id]/page.tsx
@@ -1,4 +1,3 @@
-"use client";
 import PongBoard from "./PongBoard";
 
 export default function Page({ params: { id } }: { params: { id: string } }) {