I really like the store at the beginning of every wave and your concept for the game is highly addictive. I would like to have seen a set number of waves before automatically moving to the next level and feedback to the player as to progress made to the next level. I wasn't sure how I was doing in terms of making progress. Additionally, some sound effects for towers firing as well as player taking damage and some background music would add to the ambiance of the game. I still played it for quite a while last night and this morning; it was fun.