it kinda reminded me of the game 'How Many Dudes?'. I really dig the artstyle and the concept has a lot of potential. The waves are short and sweet, I can really see myself playing more of this!
Also, I think I encountered a bug. When I was buying upgrades from wave 4 to wave 5 I upgraded the fist damage for the first time. After that, I couldn't use it, I could use all the other skills, but not the fist