Name: All Achievements
Rules: hit the gold button in under 4 minutes with less than 33% completion then achieve 100% completion. No NGG and no closing the game mid-run.
Video:
Additional: not sure if there's a good way to time this, personally I used an autosplitter to start the timer and then went back and retimed after the fact.
^ Yeah it's definitely possible to make the island jump with full running speed by bhopping to keep it, and in testing I felt like I sometimes got random speed boosts, so I'll do some more testing.
On a related (ish) note, 100% isn't possible as far as I can tell but 97% is (as if it needed to be more of a meme) and all cubes is very likely impossible.
Name: any% crouched (?)
Rules: normal any% with NGG rules + the crouch key must be held at all times you are in control of the character (I used nohboard for this but a webcam would also work)
Video:
Other info: as far as i can tell through testing, any% without NGG is impossible (mainly due to the long springboard jump to the island)