This is a very cool prototype for a game. I really like the main loop with the procedural level and being chased by all these "animals" the whole round. I will echo others' comments about it is kind of weird to have to die to progress to the next round though. I am still a little confused about how to get the other weapons too. I saw the upgrade tab but I couldn't find where to buy a pistol or shotgun, or if I had to find or get them some other way.
Your upgrade screen looks pretty big and you put some time into it, but once again as above I really didn't like dying to get to this again, along with not figuring out how to get other weapons.
The game itself was fun, just felt really incomplete without some real graphics, sounds and music going. It is a fun gameplay loop though.