few glitches A) once i got this power up that when i touch it i get a ice, and touch it again i get the red one. I touch it again it turn back to the blue one. B)If you use a heart power-up in the corner then some hearth will get stuck in the wall.
Strange that even though your engines are on, you don't press WASD. I would also like to see auto aiming turrets, animations for turning, max, turning speed, and bigger arenas.
Things to improve A) learn that human hand has 5 fingers, not 6 (change throw grenade to right mouse, etc) B) More types of zombies (heavy, ranges, etc) C) Upgradable guns.