From the rulebook: "These rules are designed for team play against an umpire-controlled zombie infestation. It is heavily influenced by '28 Days Later' and the game 'Left4Dead'. It is written for use with 20mm/25mm figures and a good source of large numbers of plastic zombies are the ones form the board game Zombies! (they also glow in the dark). The balance of the rules is on the assumption that the survivors are very heavily outnumbered, maybe 20 or 30 to one overall. Ideally the playing area should be fairly close - like an urban or wooded area - with plenty of places for the zombie hordes to lurk in ambush. In the set up there should be a number of concealed hordes - in basements, behind fences, down sewers etc. These are triggered by player action and attack. In addition there will be small groups or individual zombies scattered about the playing area."