I really liked the game! It reminded me of one I made for TriJam some time ago called "Rock Knight". The blood splats when zombies got shot are satisfying. While the only control was LMB, it didn't feel weird that it did multiple things - great job! There are some minor things to improve: player movement felt floaty... like it was ice-scating and I could shoot some enemies before they've seen me.
I had fun finishing your game! :)