Very interesting gameplay!
I think using rock, paper, scissors as a mechanic is very interesting. It was fun having to think of which button to press for each rat. I started to associate each number key on my keyboard with each weapon.
I did feel the game was a little too easy however, and felt very little threat from the rats once I learned that my character was invulnerable to them.
Overall, it's a really nice game and I enjoyed playing it! Nice job!