Success! I got to the end! The final platforming jump was pretty cool - I had to 'damage boost' off an enemy in order to get the maximum height and make it up there. The backtracking in the game from each powerup was well done and the levels were pretty fun, although a bit simple. I thought it was pretty funny to find a book on 'lava walking'. Great job on creating a full game! It felt satisfying to reach the end. The length was perfect with just enough backtracking to feel like a true metroidvania experience.
I liked the main character design! The run cycle felt a bit slow compared to his actual movement speed so maybe the frame rate could get increased a little bit. And keep an eye on the proportions of his feet — his idle frame has feet a bit larger than in the run cycle.
Would have also loved to have some sounds and music! Some of the objects could have used an audio or visual cue to communicate its purpose to the player. Like the checkpoints, I figured out were checkpoints on my own, but a little sound effect could have let me know I did in fact activate it.
Excellent work good luck on your future games!