As a test of the character controller, I'm actually very impressed.
The character moves fluently, I never got stuck against an obstacle. Controls are responsive. The default movement is quite slow, but you also have running, so the default movement would allow you to be precise (no need right now, perhaps if there were dangerous obstacles like spikes).
I love the animation of enemies being punched off-screen. However, there's no point in which attacking is not the correct response. Your punch efficiently solves all enemies in one strike. I needn't dodge or run away. Perhaps if there was a timer or a need to get somewhere fast, jumping over enemies would be more efficient, since attacking stops you in place, but you also have headbutting (which is a great mechanic, by the way).
There is a shortcut I found by jumping + headbutting to skip a portion of the course, which again leans into appealing to speedrunners who thrive on moving at top speed and finding shortcuts.
Sometimes when running down a slope, you start gliding instead of sticking to the ground.
Art-wise the game certainly has space for improvement.
Right off the bat, the rule of pixel art is to have all “pixels” maintain consistent scale, which can't be said here due to the various scaled-up variants of the orange slope which often has huge pixels in contrast with the rest of the screen.
Then the player doesn't neatly stand on sloped ground, in fact, whenever you're on a slope, you're almost certainly hovering and your feet don't touch anything.
Then there's the fact that the environment is just geometric shapes, but I accept them as a part of the test level. I could even imagine them in the final game (if they get a more unified look and consistent size).
The primary reason for the lower rating is the lack of content. There are mechanics, and those are pretty well-made, but it's a looping track from sometimes randomly resized geometric shapes, so besides killing enemies, there's not much to do, no “goal” after completing a lap around.