Successfully complete the 1965 Mansion level in story mode on the easy difficulty setting to unlock the 1965 Mansion level in arcade mode; "Horror Shocker" as a Bot Set in arcade mode; and Fishwife Mutant, Hick Hyde, Insect Mutant, Overall Mutant, Police Zombie, Girl Zombie, Skull Zombie, and Jacket Zombie as Bots in arcade mode. Note: Set "Auto Aim" to toggle, leave it on, and crouch to get easier head shots to complete this level easier.