refactor: Remove ES6 module syntax and reorder script loading

index.html

@@ -207,12 +207,12 @@
   <div id="log"></div>
 </div>
 
-<script src="game.js"></script>
 <script src="entities.js"></script>
 <script src="utils.js"></script>
 <script src="ai.js"></script>
 <script src="render.js"></script>
 <script src="events.js"></script>
+<script src="game.js"></script>
 
 <script>
 /**********************************************************************