in case i'm the only one who's played on hard, these are three things i found too frustrating:
1) I don't know how i hit this guy, though eventually i did. it's just before a save point and there's quite a way to go if you die to it which has been very often for me.
2) This part is especially difficult because you must shit on the enemy on flight to recharge the double jump, which you'll need to get past the spikes (in the picture the enemy has respawned because i went back from the checkpoint).
You only have one try to hit him, a long way from the last checkpoint and little time to prepare before the mouth enemy spits in your direction. i found this too much even for a guy who obsesses even a single game for days, but maybe i must accept i'm not as good at games as i used to.
brilliant game anyway. for anyone who liked it, i recommend scimitri's games on gamejolt, especially "bullet bubby" and "the cardinal crusade". they're hard and have a similar atmosphere.