Here's a list:
-Dying on the second TAS jump in TAS 2 (main area).
-Save fucked my self on the second-to-last jump in Insanity 2
-Jumping into the wrong startup portal in L
-Saving after the 1-frame block jump in D, and then falling off and saving in the segment below below without realizing (threw my controller across the room after this one)
-Dying on the last jump in the flippy-puzzle secret in Crimson
-Dying to Influka several hundred times in Kamilia 2
-Dying in the last part of the avoidance boss in Skyclad
-Failing quite a lot in one hard segment in Spike Master
-Dying to the final dickish attack in the 'pentagram' boss in Permanence. 3 times.
-Hitting the ceiling too hard after the second 1-frame jump in Zeus and missing the easiest jump in the game
-Downloaded Tribute
-Dying to a corner jump after a difficult segment in the red stage of Genius
That's all I can think of at the moment, and I know I have some pretty bad moments in my history of fangames.
