Hi! Thanks for the comment! Falling through that platform is intended, so the player fall on the checkpoint and go through the way to get the double jump boots. After getting it, you can double-jump directly to the platform with the enemy. =]

Hey! Thanks for the comment! I found the problem, thanks for pointing it out! The problem was with the W and UpArrow that triggered both jumps in two consecutive frames. I didn't catch when testing because I only used the Space key to jump and it had a different code to detect the input... :/

Anyway, I just uploaded the corrected version. Hope you like it! Any feedback is very appreciated! =]