Thank you for your feedback! I agree with a faster pace for the game. The current spawn system for the zombies should be faster than what I've made it to be. Again, thanks for playing my game :D
Another way to control the pacing for arena-games like this is the spawner positions. If enemies only come from one side it's obviously easier while the game is hardest when you're completly surrounded - opening up spawn places or areas one at a time can also be used to pace the game :)