Add Game object and a GameInterface for use with tests.

src/Game.php

@@ -0,0 +1,28 @@
+<?php
+declare (strict_types=1);
+
+namespace LotGD\Core;
+
+class Game implements GameInterface
+{
+    private $entityManager;
+    private $eventManager;
+
+    /**
+     * Returns the game's entity manager.
+     * @return EntityManagerInterface The game's database entity manager.
+     */
+    public function getEntityManager()
+    {
+        return $this->entityManager;
+    }
+
+    /**
+     * Returns the game's event manager.
+     * @return EventManager The game's event manager.
+     */
+    public function getEventManager()
+    {
+        return $this->eventManager;
+    }
+}

src/GameInterface.php

@@ -0,0 +1,17 @@
+<?php
+declare (strict_types=1);
+
+namespace LotGD\Core;
+
+interface GameInterface
+{
+    /**
+     * @{inheritdoc}
+     */
+    public function getEntityManager();
+
+    /**
+    * @{inheritdoc}
+     */
+    public function getEventManager();
+}