Oh yes. Me too! Out of all the game shows around on the Challenge TV channel, Crystal Maze was definitely one of my favourites along with Gladiators and Robot Wars.
I do remember a few physical games where climbing, building, and digging were essential.
So, to correct, each crystal is worth 5 seconds of time inside the dome, 100 gold after the deduction of silver meant the big prize, contestants are allowed to come out without getting locked in if they fail to complete the challenge, and lastly freeing a locked-in contestant (whether they want to or not) comes at the price of one crystal, rather than a key.
As for my favourite zone, I'm split between Futuristic and Aztec.