I don't mind which HL this is done in, it can be done in any, the only reason I say HL2 is I assumed it would have more features that would make the map easier to make.
I don't mind every 'path' being the same BUT obviously the 'short/easy' path has to be behind a different door each time.
Additionally: when players go down a path they should not be able to see the other paths - eg, connecting corridors.
Tetsu0 - you are correct except the player should not be able to take the 'suggested' choice. This door that the computer opens is always going to be a long/hard path (but never the one the player has selected). It is up to the player to decide whether to keep to their original choice (which won't be the door opened by the computer on the first button press - this is the computer basically 'eliminating' a door choice from the equation) or switch to the other unopened door.
Basically by opening the door that they do not originally choose and that the computer doesn't open, they increase their chances of getting the short path. The logic is very weird but that's just how it works! The experiment is designed to measure how long it takes players to realise they should always switch their original choice once the computer has eliminated a door choice for them.
My supervisor said 24 rooms was sufficient but more is always better. I am not keen on pushing my luck, however!
Thank you so much for your replies so far!