One Page Design

It will be 2D top-down shooter. Player will have to survive as many waves of zombies as he can. He will be in randombly generated maze so each new game will have a little bit different feeling. At the end of each wave player will be able to upgrade some stats. On end of some waves (probably 5, 10, 15, 20) will have option to choose new gun as a reward. One Page Design is attached.