The game is very nice, I don't see the boss rush aspect in it tho, but it is very good and has potential. One thing I think it's missing is the replayability factor from roguelikes, every run is the same I face the same enemy in the same order and I get the same shop items.
The art is lovely, I dig it and the controls feel great. I'd love to see this game grow after the game jam. Good job.