I don't know if it's my browser or something but the other people in the comments seem to have access to a game I don't. For me it loads and there's 3 green guys. I shoot them or they run away off screen and then nothing else ever happens, it stays at 'Wave 1'. I'm using FireFox and Linux for the record.
I didn't rate because it seems like a technical issue, but it seems like a cool game based on what other people are saying! Have a wonderful day and good luck in the Jam.