As an expansion, It seems that enemies will spawn after a certain amount of time, but they just disappear after they near the base. Over all, Really good game. Could use weapon descriptions as well as a base health upgrade. I give it a 3/5 because of the glitch.
I don't know if anyone else is experiencing this glitch, But on wave 11 just before morning all of the enemies ignore the base and just move past it. Then they collect at the back of the shop and just stay there glitching out. No damage taken, and all of the other enemies die with one shot and only grant the 2$ from the shot taken. One seems to loop the die mechanics over and over again in the middle of the street. Time still goes on, I can shoot, and what money I do get is added to my total.
 "Light Cut"){kind=icon}
 "Dawn of the Zombies"){kind=icon}
 "Toss."){kind=icon}
 "You Have To Burn The Rope"){kind=icon}