Thanks for the suggestions guys - really appreciated. I'm just checking them all out now - videos on Youtube give a good idea of the game. Will let you know which one works.
Can anyone recommend a real life simulator where you can do things like go in buildings, go up lifts, get on a bus or train etc ... It doesn't need to have an endgame (don't want to have to build it like Sim City). It's for my autistic son - he likes to explore that sort of thing, but I don't...