Loads of room for improvement.
Boss day... its quite a good idea.
If people cant pass it they must be noobs. Ive made it to lev 36 without fail. Chances on the game are low eg. Chance to get AP or items. Its really really random.
Ive given this game 5* for a great idea and awsome implementation
keep your work up buddy
If you feel more hardcore and get experience faster later on, get loads of life and let zombies hit you quite a lot, dont die tho ;) after the level you heal yourself for 150 exp where u got about 3000 for 3000 life lost etc, (1 life lost = 1 exp)
Tips :
Save and reaload the game if you want to see zombies better (blood masks some of them)
Get the upgrade that gives you more exp and then get a good shotgun and kill as close to zombies as you can for maximum exp. after that it doesnt get any easier