All levels contain specific challenge areas in which the player is required to kill a certain number of zombies in a limited time. These end with a that uses some altered form of usual gameplay, such as a long phrase or a question whose answer must be correctly typed. The console ports have "Original" and "Arcade" modes for the main storyline and "Tutorial," "Drill," and "Boss" modes for additional typing training. Most other changes are superficial, such as replacement of the weapons wielded by zombies with harmless items and equipping the AMS agents with keyboards attached to backpack Dreamcasts with oversized batteries.