Each boss has his own unique weakness that must be exposed by the players before he can be defeated. While the first boss is not very intimidating, each subsequent boss becomes more frightening as the game progresses. Terrifying monsters can be defeated by firing the nail in either a horizontal or a vertical direction. Players can be killed by their own exploding spikes, acquired throughout levels after the first boss. There are multiple exits on some levels, but all except one do not function. Only the "true" exit permits access to the next level.