In this game player takes control of a guy who got teleported back in time and found himself defending a book of undead (which caused this teleportation in the first place) in the castle from the undead hordes. Enemies come in increasingly difficulty.
Player can directly control the character - walk forward and back, while automatic shooting of a shotgun takes place at all times (as long as there are enemies in sight). There are also two abilities available at any time (two active are chosen before each wave, but there are many to choose from), each on a separate cooldown. Melee attacks happen automatically when enemy is in range (mentioned chainsaw is one of the upgrades of the melee ability). In the background we can see a blacksmith, which represents a source of income for building helping units - player can summon different units to fight with him. These include knights, archers, horsemen and more. Each unit has it's set price and specific properties, such as speed, endurance and attack value. Most of the units can be upgraded in between missions, which increases these values. Player can also buy another upgrades, such as passive archers or catapult (these are on the battlefield at all times - once purchased - and can not die). Gold is obtained by completing waves and it also drops from killed enemies (this gold must be picked up by walking over it, which can be sometimes risky as player exposes himself to damage). Game is over if player gets killed or the enemies reach the book of undead.