I got to 1000 people dead and 425 in my zombie horde and the game really started to slow down. It might just be the internet or my computer, but besides that it's really hard to move when you are in a corner and there's about 100 zombies in front of you. Maybe consider a reset button? Such as back to where you started? Not with number of kills or anything just a respawn back to the beginning of the game. Only a suggestion. Really loved the game though and I do agree that it could use a little more work I loved it how it is right no (medals are nice but I still liked it this way)