This game has a short "campaign" which is basically a drawn-out training module for the more (too) grueling survival mode. It tries to be quirky with some of the monster types (shielded wizard zombies and super-zombies), but this only succeeds in ruining the immersion. The primary mechanic is "surround the cell"; this would be great except for the RNG and the fact that it is paced poorly; the exponential growth of enemies eventually cannot be overcome. You really need the power-up items, but the game is stingy and mysterious in their application. With only 3 slots for single-use power-ups, one might think there would be some strategy in their application but they only instead act as a bottleneck, forcing the player to cycle through collected power-ups in order to avoid wasting new ones waiting for pickup. You could dedicate months to perfecting your timing - or just find another game to play because there are so many out there to choose from.