The later Infocom games — I’m thinking especially Moriarty’s evocative Wishbringer, Trinity, Beyond Zork — have much improved writing in general; it might be interesting to see what an LLM actually does with those.
A Mind Forever Voyaging has very good writing as well (and less in the way of puzzles). Of course, Hitchhiker's has great writing too.Not sure I ever played Wishbringer or Beyond Zork but Trinity is good.