Level 18, several 100 deaths (On the order of 300), gave up because fuck, it's got some really annoying gotchas.
I'm going to call bullshit on the "World's most difficult game", too, because I've played harder. See, for example, I Wanna Be The Guy: The Movie: The Game. Sure, IWBTG is almost all fake difficulty and remembering where the nasty traps are in each level. So is this. The most obvious bits of fake difficulty:
1 - Digital control, that is, I suspect, handled a little interestingly. A number of levels would be much easier if you could go slower than your usual speed.
2 - Screwy collision detection. In particular, while moving your hitbox appears to be a bit bigger than the actual onscreen icon, or at least offset from it, and the blue dots are certainly slightly larger than they should be.
Edit:
Holy crap I got it!
Spoiler:
Move in through the middle and stay close to the middle.