I love the artwork in this game -- all the crates and trucks and boarded windows got that '80s "mean streets" beat-em-up style just right. All the little details you added in the scene make it so fun to play in this world -- that Kickboxing Club poster in particular and the way you got the perspective right is so impressive! Great opening scene (nice details there, too).
Gameplay-wise, on my first several plays, I felt like I couldn't do much more than mash the punch key and try to avoid being attacked from right and left, and it felt like I'd inevitably take a single punch in between button-pushes and suffer an apparent one-hit death. For several plays it didn't feel like I was getting better. But I kept in mind that the game developer can usually beat their game easily, so I kept looking for strategies. [Spoilers ahead] I realized that duck-punching keeps the enemies at a distance and make it much less likely to take a punch from an enemy (even if it deals less damage); I realized that using jumping well allows you to corral the enemies on one side of you so you can't be punched from behind, and it also crosses-up the enemies so they punch each other (loved that); and I came to understand (correct me if I'm wrong) that even though your health meter only appears once you've been hit, the damage you've sustained from prior punches doesn't heal when your health meter disappears -- so those "one-hit deaths" weren't one-hit, they were just the final blow. And I used those strategies to beat the game.
So while there are strategies here to master, in further development, you might work on building out the combat mechanics so that the player feels like they can become more skillful at fighting, and can use different attacks on different types of enemies. Jump-kicks, leg-sweeps, dodges, weapon pick-ups, etc. -- the stuff I imagine from Double Dragon, Bad Dudes, Ninja Turtles, etc. , could be good additions. Just my two cents!
I really liked this game and would love to see more -- awesome work!