add simple crash logic

theGame/Game.cs

@@ -67,6 +67,21 @@ namespace theGame
                 rocks[i].positionX--;
             }
 
+            int deleted_rock_index = -1;
+
+            for (int i = 0; i < rocks.Count; i++)
+            {
+                if (rocks[i].positionX ==  playerCraft.positionX && rocks[i].positionY == playerCraft.positionY)
+                {
+                    deleted_rock_index = i;
+                    playerCraft.Health = playerCraft.Health - 15;
+                }
+            }
+
+            if (deleted_rock_index >= 0)
+            {
+                rocks.RemoveAt(deleted_rock_index);
+            }
         }
 	}
 }