Thanks for the comments Eric!

Your point about not having a new map is correct. I dont plan on adding more maps in the competition version of this game, but instead increase the hitpoints of enemies with each wave (=level). (much like in Space Invaders.) As far as I can tell, rules dont specify the actual representation of a new level.

With the final stage the map will increase in size to allow for a visual representation of a village and a more varied road for the enemies to walk on. I hope this course is allow otherwise I can't complete the first point of the final stage either (not within the time left that is)