diff --git a/src/Game/Controller/GameController.php b/src/Game/Controller/GameController.php
index 9a1ab78..cfc9ef6 100644
--- a/src/Game/Controller/GameController.php
+++ b/src/Game/Controller/GameController.php
@@ -4,9 +4,14 @@ declare(strict_types=1);
 namespace App\Game\Controller;
 
 use App\Game\Entity\Session;
+use App\Game\Entity\SessionSetting;
+use App\Game\Enum\SessionSettingType;
+use App\Game\Enum\SessionStatus;
 use App\Game\Repository\GameRepository;
+use App\Game\Repository\PlayerRepository;
 use App\Game\Repository\SessionRepository;
 use App\Game\Service\GameDashboardService;
+use App\Tech\Entity\User;
 use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
 use Symfony\Bundle\SecurityBundle\Security;
 use Symfony\Component\HttpFoundation\Request;
@@ -14,9 +19,16 @@ use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\Routing\Annotation\Route;
 use Symfony\Component\Security\Http\Attribute\IsGranted;
 use Symfony\Component\ExpressionLanguage\Expression;
+use Symfony\Component\DependencyInjection\Attribute\Autowire;
 
 final class GameController extends AbstractController
 {
+    public function __construct(
+        #[Autowire('%env(MERCURE_PUBLIC_URL)%')]
+        private string $mercurePublicUrl
+    ) {
+    }
+
     #[Route(path: '', name: 'game_dashboard', methods: ['GET', 'POST'])]
     #[IsGranted(new Expression("is_granted('ROLE_PLAYER') or is_granted('ROLE_ADMIN')"))]
     public function dashboard(
@@ -92,17 +104,48 @@ final class GameController extends AbstractController
         ]);
     }
 
-    #[Route(path: '/{session}', name: 'game')]
+    #[Route(path: '/{session}', name: 'game', methods: ['GET', 'POST'])]
     #[IsGranted(new Expression("is_granted('ROLE_PLAYER') or is_granted('ROLE_ADMIN')"))]
     #[IsGranted('SESSION_VIEW', subject: 'session')]
     public function index(
         Session $session,
+        Request $request,
         Security $security,
-        \App\Game\Repository\PlayerRepository $playerRepository
+        PlayerRepository $playerRepository,
+        GameDashboardService $dashboardService
     ): Response
     {
         $user = $security->getUser();
+        if (!$user instanceof User) {
+            throw $this->createAccessDeniedException();
+        }
+
         $player = $playerRepository->findOneBy(['session' => $session, 'user' => $user]);
+
+        if ($request->isMethod('POST') && $request->request->has('toggle_ready')) {
+            $dashboardService->toggleReady($session, $user);
+            return $this->redirectToRoute('game', ['session' => $session->getId()]);
+        }
+
+        // Periodically check readiness timeout
+        $dashboardService->checkAllPlayersReady($session);
+
+        if ($session->getStatus() === SessionStatus::READY) {
+            $isReady = false;
+            if ($player) {
+                $settingName = SessionSettingType::tryFrom('ReadyAtForPlayer' . $player->getScreen());
+                if ($settingName) {
+                    $isReady = $session->getSettings()->exists(fn($i, SessionSetting $s) => $s->getName() === $settingName && $s->getPlayer() === $player);
+                }
+            }
+
+            return $this->render('game/waiting.html.twig', [
+                'session' => $session,
+                'isReady' => $isReady,
+                'mercure_public_url' => $this->mercurePublicUrl,
+            ]);
+        }
+
         $screen = $player ? $player->getScreen() : 0;
 
         return $this->render('game/index.html.twig', [
diff --git a/src/Game/Entity/Player.php b/src/Game/Entity/Player.php
index e9802f6..a99bd7c 100644
--- a/src/Game/Entity/Player.php
+++ b/src/Game/Entity/Player.php
@@ -60,7 +60,7 @@ class Player
         return $this->screen;
     }
 
-    public function setScreen(int $screen): static
+    public function setScreen(?int $screen): static
     {
         $this->screen = $screen;
 
diff --git a/src/Game/Enum/SessionSettingType.php b/src/Game/Enum/SessionSettingType.php
index 36279fb..7788245 100644
--- a/src/Game/Enum/SessionSettingType.php
+++ b/src/Game/Enum/SessionSettingType.php
@@ -60,4 +60,14 @@ enum SessionSettingType: string
     case SPECIAL_REPORT_CODE_DOYLE = 'SpecialReportCodeDoyle';
     case SPECIAL_REPORT_CODE_VEGA = 'SpecialReportCodeVega';
     case SPECIAL_REPORT_CODE_LENNOX = 'SpecialReportCodeLennox';
+    case READY_AT_FOR_PLAYER1 = 'ReadyAtForPlayer1';
+    case READY_AT_FOR_PLAYER2 = 'ReadyAtForPlayer2';
+    case READY_AT_FOR_PLAYER3 = 'ReadyAtForPlayer3';
+    case READY_AT_FOR_PLAYER4 = 'ReadyAtForPlayer4';
+    case READY_AT_FOR_PLAYER5 = 'ReadyAtForPlayer5';
+    case READY_AT_FOR_PLAYER6 = 'ReadyAtForPlayer6';
+    case READY_AT_FOR_PLAYER7 = 'ReadyAtForPlayer7';
+    case READY_AT_FOR_PLAYER8 = 'ReadyAtForPlayer8';
+    case READY_AT_FOR_PLAYER9 = 'ReadyAtForPlayer9';
+    case READY_AT_FOR_PLAYER10 = 'ReadyAtForPlayer10';
 }
diff --git a/src/Game/Service/GameDashboardService.php b/src/Game/Service/GameDashboardService.php
index efa2887..b53aa7b 100644
--- a/src/Game/Service/GameDashboardService.php
+++ b/src/Game/Service/GameDashboardService.php
@@ -15,6 +15,9 @@ use App\Game\Repository\SessionRepository;
 use App\Tech\Entity\User;
 use Doctrine\ORM\EntityManagerInterface;
 use Symfony\Component\Security\Core\User\UserInterface;
+use Symfony\Component\Mercure\HubInterface;
+use Symfony\Component\Mercure\Update;
+use Symfony\Component\DependencyInjection\Attribute\Autowire;
 
 final class GameDashboardService
 {
@@ -22,6 +25,9 @@ final class GameDashboardService
         private readonly GameRepository $gameRepository,
         private readonly SessionRepository $sessionRepository,
         private readonly EntityManagerInterface $entityManager,
+        private readonly HubInterface $hub,
+        #[Autowire('%env(MERCURE_TOPIC_BASE)%')]
+        private readonly string $mercureTopicBase,
     ) {
     }
 
@@ -66,13 +72,17 @@ final class GameDashboardService
 
         $player = new Player();
         $player->setUser($user);
-        $player->setSession($session);
+        $session->addPlayer($player);
 
         $this->entityManager->persist($session);
         $this->entityManager->persist($player);
 
         $this->entityManager->flush();
 
+        if (count($session->getPlayers()) === $session->getGame()->getNumberOfPlayers()) {
+            $this->startSession($session);
+        }
+
         return $session;
     }
 
@@ -107,12 +117,16 @@ final class GameDashboardService
 
         $player = new Player();
         $player->setUser($user);
-        $player->setSession($session);
+        $session->addPlayer($player);
 
         $this->entityManager->persist($player);
 
         $this->entityManager->flush();
 
+        if (count($session->getPlayers()) === $session->getGame()->getNumberOfPlayers()) {
+            $this->startSession($session);
+        }
+
         return true;
     }
 
@@ -122,7 +136,7 @@ final class GameDashboardService
             return false;
         }
 
-        if ($session->getStatus() !== SessionStatus::CREATED || $session->getTimer() > 0) {
+        if (!in_array($session->getStatus(), [SessionStatus::CREATED, SessionStatus::READY]) || $session->getTimer() > 0) {
             return false;
         }
 
@@ -138,6 +152,14 @@ final class GameDashboardService
             return false;
         }
 
+        if ($session->getStatus() === SessionStatus::READY) {
+            $session->setStatus(SessionStatus::CREATED);
+            // Clear assignments for all remaining players since the game needs to be "started" again
+            foreach ($session->getPlayers() as $player) {
+                $player->setScreen(null);
+            }
+        }
+
         // Remove player specific settings (like rights)
         foreach ($session->getSettings() as $setting) {
             if ($setting->getPlayer() === $playerToDelete) {
@@ -240,6 +262,14 @@ final class GameDashboardService
             return false;
         }
 
+        // Clean up any existing assignments (e.g. if we reverted from READY to CREATED)
+        foreach ($session->getSettings() as $setting) {
+            if ($setting->getPlayer() !== null) {
+                $session->removeSetting($setting);
+                $this->entityManager->remove($setting);
+            }
+        }
+
         // Shuffle players to assign random screens
         shuffle($players);
 
@@ -257,6 +287,113 @@ final class GameDashboardService
         return true;
     }
 
+    public function toggleReady(Session $session, User $user): bool
+    {
+        if ($session->getStatus() !== SessionStatus::READY) {
+            return false;
+        }
+
+        $player = null;
+        foreach ($session->getPlayers() as $p) {
+            if ($p->getUser() === $user) {
+                $player = $p;
+                break;
+            }
+        }
+
+        if (!$player) {
+            return false;
+        }
+
+        $settingName = SessionSettingType::tryFrom('ReadyAtForPlayer' . $player->getScreen());
+        if (!$settingName) {
+            return false;
+        }
+
+        /** @var \App\Game\Repository\SessionSettingRepository $settingRepo */
+        $settingRepo = $this->entityManager->getRepository(SessionSetting::class);
+        $setting = $settingRepo->getSetting($session, $settingName, $player);
+
+        if ($setting) {
+            $session->removeSetting($setting);
+            $this->entityManager->remove($setting);
+        } else {
+            $setting = new SessionSetting();
+            $setting->setSession($session);
+            $setting->setPlayer($player);
+            $setting->setName($settingName);
+            $setting->setValue((string)(new \DateTime())->getTimestamp());
+            $this->entityManager->persist($setting);
+        }
+
+        $this->checkAllPlayersReady($session);
+        $this->entityManager->flush();
+
+        $topic = $this->mercureTopicBase . '/game/hub-' . $session->getId();
+        $this->hub->publish(new Update($topic, json_encode(['type' => 'player_ready', 'player' => $player->getScreen(), 'ready' => !$setting])));
+
+        return true;
+    }
+
+    public function checkAllPlayersReady(Session $session): void
+    {
+        if ($session->getStatus() !== SessionStatus::READY) {
+            return;
+        }
+
+        $players = $session->getPlayers();
+        $numPlayers = $session->getGame()->getNumberOfPlayers();
+
+        if (count($players) < $numPlayers) {
+            return;
+        }
+
+        $readyPlayersCount = 0;
+        $now = new \DateTime();
+
+        /** @var \App\Game\Repository\SessionSettingRepository $settingRepo */
+        $settingRepo = $this->entityManager->getRepository(SessionSetting::class);
+
+        foreach ($players as $player) {
+            $settingName = SessionSettingType::tryFrom('ReadyAtForPlayer' . $player->getScreen());
+            if (!$settingName) {
+                continue;
+            }
+
+            $setting = $settingRepo->getSetting($session, $settingName, $player);
+            if ($setting) {
+                $readyAtTimestamp = (int)$setting->getValue();
+                // Check timeout: 1 minute = 60 seconds
+                if (($now->getTimestamp() - $readyAtTimestamp) > 60) {
+                    $session->removeSetting($setting);
+                    $this->entityManager->remove($setting);
+                } else {
+                    $readyPlayersCount++;
+                }
+            }
+        }
+
+        if ($readyPlayersCount === $numPlayers) {
+            $session->setStatus(SessionStatus::PLAYING);
+            $this->entityManager->persist($session);
+
+            // Clean up ready settings
+            foreach ($players as $player) {
+                $settingName = SessionSettingType::tryFrom('ReadyAtForPlayer' . $player->getScreen());
+                if ($settingName) {
+                    $setting = $settingRepo->getSetting($session, $settingName, $player);
+                    if ($setting) {
+                        $session->removeSetting($setting);
+                        $this->entityManager->remove($setting);
+                    }
+                }
+            }
+
+            $topic = $this->mercureTopicBase . '/game/hub-' . $session->getId();
+            $this->hub->publish(new Update($topic, json_encode(['type' => 'all_ready'])));
+        }
+    }
+
     public function generateInviteCode(Session $session, UserInterface $user, bool $isAdmin): ?string
     {
         // Security check: is user part of this session?
diff --git a/src/Game/Service/GameResponseService.php b/src/Game/Service/GameResponseService.php
index b298e27..e2e746c 100644
--- a/src/Game/Service/GameResponseService.php
+++ b/src/Game/Service/GameResponseService.php
@@ -12,6 +12,7 @@ use Doctrine\ORM\EntityManagerInterface;
 use Symfony\Bundle\SecurityBundle\Security;
 use Symfony\Component\Mercure\HubInterface;
 use Symfony\Component\Mercure\Update;
+use Symfony\Component\DependencyInjection\Attribute\Autowire;
 
 class GameResponseService
 {
@@ -22,6 +23,8 @@ class GameResponseService
         private HubInterface $hub,
         private EntityManagerInterface $entityManager,
         private string $projectDir,
+        #[Autowire('%env(MERCURE_TOPIC_BASE)%')]
+        private string $mercureTopicBase,
     ) {
     }
 
@@ -375,7 +378,7 @@ class GameResponseService
             $this->entityManager->flush();
 
             // Notify the player that their codes have changed
-            $topic = $_ENV['MERCURE_TOPIC_BASE'] . '/game/hub-' . $session->getId();
+            $topic = $this->mercureTopicBase . '/game/hub-' . $session->getId();
             $notification = "Security Alert: One of your verify codes was shared and has been regenerated.";
             // We send it only to this player (screen)
             $this->hub->publish(new Update($topic, json_encode([$screen, $notification])));
@@ -662,7 +665,7 @@ class GameResponseService
             $this->entityManager->persist($everyoneVerifiedSetting);
             $this->entityManager->flush();
 
-            $topic = $_ENV['MERCURE_TOPIC_BASE'] . '/game/hub-' . $session->getId();
+            $topic = $this->mercureTopicBase . '/game/hub-' . $session->getId();
             $message = "Mainframe Help Modus: Agents Doyle, Vega and Lennox rapports have been updated with coded messages.";
             $this->hub->publish(new Update($topic, json_encode([0, $message])));
         }
diff --git a/templates/game/waiting.html.twig b/templates/game/waiting.html.twig
new file mode 100644
index 0000000..b2c26f0
--- /dev/null
+++ b/templates/game/waiting.html.twig
@@ -0,0 +1,96 @@
+{% extends 'base.html.twig' %}
+
+{% block title %}Waiting for players - {{ session.game.name }}{% endblock %}
+
+{% block body %}
+<div class="container mt-5">
+    <div class="row justify-content-center">
+        <div class="col-md-8">
+            <div class="card shadow-sm">
+                <div class="card-header bg-primary text-white">
+                    <h3 class="card-title mb-0">Waiting for all players to be ready</h3>
+                </div>
+                <div class="card-body">
+                    <h4>{{ session.game.name }}</h4>
+                    <p>Welcome to the game! Please wait for all players to join and signal they are ready to start.</p>
+
+                    <div class="alert alert-info">
+                        <strong>Game Information:</strong>
+                        <ul class="mb-0">
+                            <li>Number of players: {{ session.game.numberOfPlayers }}</li>
+                            <li>Current players: {{ session.players|length }} / {{ session.game.numberOfPlayers }}</li>
+                        </ul>
+                    </div>
+
+                    <div class="mt-4">
+                        <h5>Players status:</h5>
+                        <ul class="list-group">
+                            {% for player in session.players %}
+                                <li class="list-group-item d-flex justify-content-between align-items-center">
+                                    {{ player.user.username }}
+                                    {% set playerReady = false %}
+                                    {% set settingName = 'ReadyAtForPlayer' ~ player.screen %}
+                                    {% for setting in session.settings %}
+                                        {% if setting.name.value == settingName and setting.player == player %}
+                                            {% set playerReady = true %}
+                                        {% endif %}
+                                    {% endfor %}
+
+                                    {% if playerReady %}
+                                        <span class="badge bg-success">Ready</span>
+                                    {% else %}
+                                        <span class="badge bg-secondary">Not ready</span>
+                                    {% endif %}
+                                </li>
+                            {% endfor %}
+                        </ul>
+                    </div>
+
+                    <hr>
+
+                    <form method="post" class="mt-4">
+                        <div class="form-check form-switch mb-3">
+                            <input class="form-check-input" type="checkbox" id="toggle_ready" name="toggle_ready" onchange="this.form.submit()" {{ isReady ? 'checked' : '' }}>
+                            <label class="form-check-label" for="toggle_ready">
+                                <strong>I am ready to start!</strong>
+                            </label>
+                        </div>
+                        <p class="text-muted small">
+                            Note: If all players are not ready within 1 minute of you checking this, your status will be reset automatically.
+                        </p>
+                    </form>
+
+                    <div class="mt-3">
+                        <a href="{{ path('game_dashboard') }}" class="btn btn-outline-secondary">Back to Dashboard</a>
+                    </div>
+                </div>
+            </div>
+        </div>
+    </div>
+</div>
+
+<div id="mercure-config"
+     data-mercure-public-url="{{ mercure_public_url|e('html_attr') }}"
+     data-topic="{{ (mercure_topic_base ~ '/game/hub-' ~ session.id)|e('html_attr') }}"
+     style="display:none">
+</div>
+
+<script>
+    const config = document.getElementById('mercure-config');
+    const publicUrl = config.dataset.mercurePublicUrl;
+    const topic = config.dataset.topic;
+
+    if (publicUrl && topic) {
+        const url = new URL(publicUrl);
+        url.searchParams.append('topic', topic);
+
+        const eventSource = new EventSource(url);
+        eventSource.onmessage = event => {
+            const data = JSON.parse(event.data);
+            if (data.type === 'all_ready' || data.type === 'player_ready') {
+                window.location.reload();
+            }
+        };
+    }
+</script>
+{% endblock %}
diff --git a/tests/Game/GameDashboardServiceTest.php b/tests/Game/GameDashboardServiceTest.php
index 53caef5..644308e 100644
--- a/tests/Game/GameDashboardServiceTest.php
+++ b/tests/Game/GameDashboardServiceTest.php
@@ -8,12 +8,14 @@ use App\Game\Entity\Player;
 use App\Game\Entity\Session;
 use App\Game\Entity\SessionSetting;
 use App\Game\Enum\GameStatus;
+use App\Game\Enum\SessionStatus;
 use App\Game\Enum\SessionSettingType;
 use App\Game\Service\GameDashboardService;
 use App\Tech\Entity\User;
 use Doctrine\ORM\EntityManagerInterface;
 use App\Game\Repository\GameRepository;
 use App\Game\Repository\SessionRepository;
+use Symfony\Component\Mercure\HubInterface;
 use PHPUnit\Framework\TestCase;
 
 class GameDashboardServiceTest extends TestCase
@@ -21,6 +23,7 @@ class GameDashboardServiceTest extends TestCase
     private $entityManager;
     private $gameRepository;
     private $sessionRepository;
+    private $hub;
     private $service;
 
     protected function setUp(): void
@@ -28,11 +31,14 @@ class GameDashboardServiceTest extends TestCase
         $this->entityManager = $this->createMock(EntityManagerInterface::class);
         $this->gameRepository = $this->createMock(GameRepository::class);
         $this->sessionRepository = $this->createMock(SessionRepository::class);
+        $this->hub = $this->createMock(HubInterface::class);
 
         $this->service = new GameDashboardService(
             $this->gameRepository,
             $this->sessionRepository,
-            $this->entityManager
+            $this->entityManager,
+            $this->hub,
+            'http://localhost/topic'
         );
     }
 
@@ -193,24 +199,219 @@ class GameDashboardServiceTest extends TestCase
         $this->assertCount(1, $session->getPlayers());
     }
 
-    public function testLeaveSessionDeletesSessionIfLastPlayer(): void
+    public function testToggleReady(): void
     {
         $user = new User();
+        $game = new Game();
+        $game->setNumberOfPlayers(1);
         $session = new Session();
-        $session->setStatus(\App\Game\Enum\SessionStatus::CREATED);
-        $session->setTimer(0);
+        $session->setGame($game);
+        $session->setStatus(SessionStatus::READY);
 
         $player = new Player();
         $player->setUser($user);
-        $player->setSession($session);
+        $player->setScreen(1);
         $session->addPlayer($player);
 
-        $this->entityManager->expects($this->exactly(2))
+        $repo = $this->createMock(\App\Game\Repository\SessionSettingRepository::class);
+        $this->entityManager->method('getRepository')
+            ->willReturn($repo);
+
+        // First call: toggle ON
+        $repo->expects($this->atLeastOnce())
+            ->method('getSetting')
+            ->willReturn(null); // No setting initially
+
+        $this->entityManager->expects($this->atLeastOnce())
+            ->method('persist')
+            ->with($this->callback(function($entity) {
+                return $entity instanceof SessionSetting && $entity->getName() === SessionSettingType::READY_AT_FOR_PLAYER1;
+            }));
+
+        $result = $this->service->toggleReady($session, $user);
+        $this->assertTrue($result);
+    }
+
+    public function testCheckAllPlayersReadyTransitionsStatus(): void
+    {
+        $game = new Game();
+        $game->setNumberOfPlayers(2);
+        $session = new Session();
+        $session->setGame($game);
+        $session->setStatus(SessionStatus::READY);
+
+        $player1 = new Player();
+        $player1->setScreen(1);
+        $session->addPlayer($player1);
+
+        $player2 = new Player();
+        $player2->setScreen(2);
+        $session->addPlayer($player2);
+
+        $repo = $this->createMock(\App\Game\Repository\SessionSettingRepository::class);
+        $this->entityManager->method('getRepository')
+            ->willReturn($repo);
+
+        $setting1 = new SessionSetting();
+        $setting1->setName(SessionSettingType::READY_AT_FOR_PLAYER1);
+        $setting1->setValue((string)time());
+        $setting1->setPlayer($player1);
+
+        $setting2 = new SessionSetting();
+        $setting2->setName(SessionSettingType::READY_AT_FOR_PLAYER2);
+        $setting2->setValue((string)time());
+        $setting2->setPlayer($player2);
+
+        $repo->method('getSetting')
+            ->willReturnCallback(function($s, $name, $p) use ($setting1, $setting2) {
+                if ($name === SessionSettingType::READY_AT_FOR_PLAYER1) return $setting1;
+                if ($name === SessionSettingType::READY_AT_FOR_PLAYER2) return $setting2;
+                return null;
+            });
+
+        $this->service->checkAllPlayersReady($session);
+
+        $this->assertEquals(SessionStatus::PLAYING, $session->getStatus());
+    }
+
+    public function testCheckAllPlayersReadyTimeouts(): void
+    {
+        $game = new Game();
+        $game->setNumberOfPlayers(2);
+        $session = new Session();
+        $session->setGame($game);
+        $session->setStatus(SessionStatus::READY);
+
+        $player1 = new Player();
+        $player1->setScreen(1);
+        $session->addPlayer($player1);
+
+        $player2 = new Player();
+        $player2->setScreen(2);
+        $session->addPlayer($player2);
+
+        $repo = $this->createMock(\App\Game\Repository\SessionSettingRepository::class);
+        $this->entityManager->method('getRepository')
+            ->willReturn($repo);
+
+        $setting1 = new SessionSetting();
+        $setting1->setName(SessionSettingType::READY_AT_FOR_PLAYER1);
+        $setting1->setValue((string)(time() - 70)); // Timed out
+        $setting1->setPlayer($player1);
+        $session->addSetting($setting1);
+
+        $repo->method('getSetting')
+            ->willReturnCallback(function($s, $name, $p) use ($setting1) {
+                if ($name === SessionSettingType::READY_AT_FOR_PLAYER1) return $setting1;
+                return null;
+            });
+
+        $this->entityManager->expects($this->once())
+            ->method('remove')
+            ->with($setting1);
+
+        $this->service->checkAllPlayersReady($session);
+
+        $this->assertEquals(SessionStatus::READY, $session->getStatus());
+    }
+
+    public function testJoinSessionTriggersStartSessionWhenFull(): void
+    {
+        $user = new User();
+        $user->setUsername('testuser');
+        $game = new Game();
+        $game->setNumberOfPlayers(2);
+        $session = new Session();
+        $session->setGame($game);
+        $session->setStatus(\App\Game\Enum\SessionStatus::CREATED);
+
+        $existingUser = new User();
+        $existingUser->setUsername('existing');
+        $existingPlayer = new Player();
+        $existingPlayer->setUser($existingUser);
+        $session->addPlayer($existingPlayer);
+
+        $setting = new SessionSetting();
+        $setting->setSession($session);
+        $setting->setName(SessionSettingType::INVITE_CODE);
+        $setting->setValue('abc-123');
+
+        $repo = $this->createMock(\Doctrine\ORM\EntityRepository::class);
+        $this->entityManager->method('getRepository')
+            ->willReturn($repo);
+
+        $repo->method('findOneBy')
+            ->willReturn($setting);
+
+        // Expectation:
+        // 1. Persist new Player
+        // 2. Persist Player 1 (existing) screen update
+        // 3. Persist Player 2 (new) screen update
+        // 4. Persist Session status update
+        // 5. 5 Settings for Player 1
+        // 6. 5 Settings for Player 2
+        // Total = 1 + 1 + 1 + 1 + 5 + 5 = 14 persists
+        $this->entityManager->expects($this->exactly(14))
+            ->method('persist');
+
+        $result = $this->service->joinSession('abc-123', $user);
+
+        $this->assertTrue($result);
+        $this->assertEquals(\App\Game\Enum\SessionStatus::READY, $session->getStatus());
+    }
+
+    public function testLeaveSessionRevertsFromReady(): void
+    {
+        $user = new User();
+        $user->setUsername('testuser');
+        $session = new Session();
+        $session->setStatus(\App\Game\Enum\SessionStatus::READY);
+        $session->setTimer(0);
+
+        $player1 = new Player();
+        $player1->setUser($user);
+        $player1->setScreen(1);
+        $player1->setSession($session);
+        $session->addPlayer($player1);
+
+        $player2 = new Player();
+        $player2->setUser(new User());
+        $player2->setScreen(2);
+        $player2->setSession($session);
+        $session->addPlayer($player2);
+
+        $this->entityManager->expects($this->exactly(1))
             ->method('remove');
-            // 1. Player, 2. Session
+            // 1. Player1, any settings (none in this test setup)
 
         $result = $this->service->leaveSession($session, $user);
 
         $this->assertTrue($result);
+        $this->assertEquals(\App\Game\Enum\SessionStatus::CREATED, $session->getStatus());
+        $this->assertNull($player2->getScreen());
+    }
+
+    public function testCreateSessionForOnePlayerGame(): void
+    {
+        $game = new Game();
+        $game->setStatus(GameStatus::OPEN);
+        $game->setNumberOfPlayers(1);
+
+        $user = new User();
+        $user->setUsername('testuser');
+
+        // 1. Session persist
+        // 2. Player persist
+        // 3. Player screen persist (during startSession)
+        // 4. Session status persist (during startSession)
+        // 5. 5 Settings for Player (during startSession)
+        // Total = 1 + 1 + 1 + 1 + 5 = 9 persists
+        $this->entityManager->expects($this->exactly(9))
+            ->method('persist');
+
+        $session = $this->service->createSession($game, $user, false);
+
+        $this->assertInstanceOf(Session::class, $session);
+        $this->assertEquals(\App\Game\Enum\SessionStatus::READY, $session->getStatus());
     }
 }