Undercover

duke6666

Crypt

For me that one was like entirely new in the game. I can't recall something equivalent in design. It was big fun to me to solve it.

Tilu

Chimney Sweep

VisD

Zebes

Completely baffled, after umpteen tries I was still nowhere near solving it.  Then it clicked and I had to kick myself for not seeing the solution, so simple, yet so tricky (for me).

Roskoe

Siege

Gridlock

Gauntlet

For me, tricky, I couldn't improve on 2 off for ages till I tried a slight direction change.

Dead Weight

Cubicle

Kept on making the same move keeping me at 2 off.  Eventually saw it.  Nice level.

13 Floors Up

I found a few ways to make 2 off, no closer.