what do you think the trickiest mate of all time is, it can be a puzzle too

darn, that one is tough.. the fastest I have it worked out to so far is 521 moves ;)

Can someone make this puzzle interactive. I tried from "insert position or game" but i couldn't...

Yes, it looks a lot faster than 517 moves.  In fact after Qxb7, shredderchess.com lists that Black loses in 16.

Oops, actually I think it is black to move

lol

do you have the answer?