Love the game! Its a very well made, but I feel there is one very big issue that you should fix after the jam is over. You should reduce the screen shake when the weapons are firing a lot of bullets, I played till wave 20, but then had to stop due to the nauseating feeling due to high screen shake.
Also, a few tips to make the game more fun. You should reduce the reload time for the sniper and rocket launcher, because that does not suit the fast paced nature of your game. It will make them overpowered, so be sure to nerf them if you follow my advice. Secondly, should give the player a reason to move around. In its current state, I could just get a fast firing gun, such as the machine gun, and then camp in one corner of the map. I did not find the chest you placed until i decided to find a way to complete the game.
All in all, fantastic work! Love the art and music, and the game was well made. Keep it up!