Nice little shooter you have made! I did experience some small stuttering at the start of waves and when enemies spawned, but I'm guessing that's probably really just a problem in the browser version of the game. Game felt pretty nice to play, movement and jumping were good. I think for this style of game I would prefer to fight against more enemies with less health. Since each wave really only has like 1-3 enemies and they all take multiple shots to kill, feels a bit slow in that regard. I hope you keep working on this idea, great job!