I wish you had added a 1 player mode to the game. You already had most of the options needed to make it a wave based survival game in the menu anyways. As I had no one to play this with I played it like a 1 player game anyways by moving the other character into a corner and trying to protect him and survive for as long as possible with the constantly spawning enemies.
Ran well on a low powered Arch Linux laptop and the only bug I encountered was the fact that if both players fell into a pit the game would say they had both won :P.