Warning- old-school difficulty
A lot of the game's difficulty comes from finicky little things, though. For instance, your attacks have lots of reach but very little vertical vertical range, causing enemies to shimmy past you while you swing at thin air. Also, despite the game mocking you for using the easy difficulty, hard mode only make enemies absorb about a billion hits before they die; adding more enemies or making them smarter/trickier would be neat.
My favorite stage was the robot war, if only for the unexpected enemy design. The aliens were cool too, but the zombies were just generic video game zombies. Despite that, the art design is the best part of this game.