First off, congrats! You made a game! That isn't an easy task and you should feel great about following it through! The game felt really solid and I could see myself running through it again.
So now let's get into that constructive criticism stuff!
- Right off the bat, I was confused by the controls. WASD doesn't feel natural for most platformers, and I saw my hand shoot to the Arrow Keys only to find them unresponsive. WASD just feels weird, and since it was not really described as the main control scheme in a tutorial anywhere, I could see people getting confused.
- So, I can see that you wanted to make a "rage" game. To make a rage game feel good, you need to make the player feel like it's their fault they died, and not the developer or rng. Now while the game felt extremely responsive, and I feel a few of the deaths were my fault, the extreme knockback completely broke this experience. It felt way to extreme and random, and it was frustrating to see my character fly all the way across the level into a pit of fire. Yanking away control from the player is a horrible thing to do, and it made the game feel unfair and it gave me the impression it wasn't my fault but the games for my deaths.
- This is simply a nit-pick as a pixel artist, but you break pixel scale quite a lot. This isn't a big deal since you are new, but you should always try to prevent unnecessary breaking of an established pixel scale.
- The first stage of the boss fight felt entirely luck based, as I always seem to get hit when jumping across to slam dunk the head in.
- I rage quitted on the second stage of the boss fight, simply because at that point health doesn't matter. If you get hit once you're basically dead, as the knockback will either launch you all the way off or you will lose too much time bouncing around off everything.
- Also, one of the cutscenes has a problem with the dialogue box going too far off screen. You also should make pressing enter finish the typewriter effect if pressed while a character is still talking, and then have the player press enter again to continue the dialogue. I found myself bi-accidently skipping dialogue.
- This one is more of a question, but what do coins do exactly? They seem kinda worthless, which isn't a good thing...
Don't let me get you down, this is wonderful work, especially for your first game! (Wish I could say the same about mine :/) Keep your head strong, take in as much feedback as you can, and make some awesome things!