Great base so far!
The lighting is nice a moody, and the sprites look good. I like the split with the stairs and the verticle hallway. It's a great way to show the equal importance of both Height and Depth in exploration.
The bit where you had to Dash then jump took me a minute to work out. I kept trying to Dash mid-air, then I'd fall down and sometimes trigger a Brawl on the left again. I also couldn't beat the Boss after a few tries. I'd have tried some more if there was a checkpoint, but it was too annoying to go through it all again.
I guess the main thing is just that the combat needs development. Right now the best strategy is to just keep punching and let the enemies walk into you, since the damage window is so wide. I tried to be a bit fancier, blocking and alternating, but it never seemed that effective, and I'd often get stun locked between two enemies and die. Maybe this is why I was ill-prepared for the Boss. Or maybe it's just hard IDK.
(Also good call going for a 2D look in a 3D world. I've been experiementing with verticle Brawler elements for my game, and trying to do that shit in 2D is a headache! I wouldn't mind a little feedback too if you can hit me back.)