Zombie Apocalypse, is by no means a great game, it's a fun game.
The alternative game modes, which include 'Chainsaw Only', is a nice option to have, when the standard single player game mode becomes tiring and monotonous, which it ultimately does after several levels in one sitting.
Aside from being a fun and competitive game, there are many aspects of this games that are poorly executed and needs improvement. The lack of different levels and weaponry makes the game seem a bit repetitive.
If you are a fan of killing larges masses of the undead, Zombie Apocalypse, is right up your alley and will not disappoint. Despite many flaws in the game and the lack of originality, the $10 asking price for this game is manageable and well worth it.