I’d like to play a star turtle using iOS, but alas it will not let me type.

RIP SIR TERRY.

Lambda Moo was not about Discworld but there were crazy experiments there, even in-game Gopher client I think.

Also, if you like Discworld, Nethack has tons of surprises because of it. The Tourist role was straightly taken from the books. And you can find in-game extracts from the novels too, giving you EXP if you read them.