At first i was like WTF, after 45 min... its fun. Once you learn how the aiming works its much better, the 50pt power up I only seen once over that time- and i didnt catch what it was then :P Never figured out the square powerup.
Fun game but i dont get why they dont auto infect? After three or so spawns you cant move them into cells faster anyways. Its useless. Biohazard makes more than two useful other than that theres no point other than antibody protection.