I recently caught a bit of The Great Escape on TV (I’ve watched it countless times) which, combined with this talk of saboteurs and rats, makes me think that maybe the setting needs to be changed for this type of game mechanic to really work.
Imagine a game where it’s basically the set up of the film - the players are all in a prison and from different backgrounds, and total cooperation is required to escape (but there’d be the option to go rogue, like Steve McQueen does at first). Missions along the way would be solving all of the problems, like in the film, and building the tunnel (or whatever chosen method) without getting caught. You have to interact with the guards to get items through pickpocketing and blackmail (like James Garner) and there’s a risk of spies and informants (although there weren’t spies in the film, and that kind of takes away from the uplifting spirit-of-cooperation theme that makes the film so great).
The setting is changeable to anywhere, I had thought a space slaver camp in Charybdis maybe; keeping the WW2 setting would be just as interesting but spies and double crosses would be more appropriate in a space prison. The BDW setting would work too.