Thanks a lot for your feedback !
We had no time to introduce a proper tutorial or visual feedback for the tiles effect :/. It applies a score AND damage multiplier the more "circles" you have. In the final waves it's actually crucial to have these circles to be efficient. These last waves are worth 1/3 of the points.
And we agree the art of AA is just too good. Singlehandedly make me want to work my ass off on the game.
I will probably update the game with an webGL version, better balancing and menus and the 20 or so voicelines we didn't had time to put in.