I haven't been able to get too far (it's very challenging) but what I've played I've liked it, but heres what I thought
The aesthetics are great! The limited color palette is used extremely well, everything looks great. The animations are nice and smooth, great job.
Music is good, definitely has that retro vibe to it. I personally think the dash affect is a little too piercing though, but that's my opinion.
Gameplay, for the most part, was fun but very difficult.
There is an issue I had where every so often I would press the jump button and he would not jump, resulting in me dying. Not sure if it was because a previous animation was still playing or if I pressed it to early, but it didn't *feel* right not to jump, if that makes sense.
The black birds I take issue with. They take more than one hit to kill but because you have to be so precise with the attack and the animation is quite slow, I seem to shoot them and before I can recover they have got me. They don't slow down when you hit them, so it feels a bit unfair on some of the trickier platforming sections.
I think the collision detection for the player could be increase a little bit I found that I would fall off ledges after a jump quite a lot because you have to be so precise. I get that it needs to be precise but there doesn't seem to be much tolerance here.
Coyote time works well. Ledge grabbing works well, however, a little bug if you move super close to the edge whilst on top of the ledge and fall off, you'll ledge grab facing the wrong direction, nothing that affects gameplay just a little thing
Again, these are all my opinion. I think you succeeded in doing what you set out to do, the game is challenging, the gameplay for the most part feels good, sounds great all wrapped up in a nice looking package. The fact that you did it in one month is quite the feat, very impressive work.