Think the context would be say in a movie our heros have got into the bad guy's base, and there's this rubiks cube like puzzle object they have to solve, which is especially difficult to solve it's a ... ?
The best words I've come up with are 'condundrum' and 'enigma' but neither of these seem to fit appropriately.
Condundrum seems to fit more difficulty facing decision making. And enigma is a mysterious problem.
I was sure that there was a word for it, but perhaps there isn't.