I've tried playing this twice now, and I could swear there aren't enough keys for all the doors.
First time, I kind of sequence-broke with wall jumps, went and found all the runes but never found the triple jump, then ended up locked out of the yellow part with the door. So I assumed there must have been a key behind that door. Second time I went straight there, unlocked it with my first key after getting the powerups, and no key back there. I ended up screwed for the rune in the blue area (the one that needs like three keys, go figure).
Is it badly designed, or am I just missing a room every time? It's pretty frustrating. (I'm playing this as a break from the Doomzone in Skelemania, and it's not helping my rage.)