MUDs don’t count unless they were designed around a very very small player cap, especially for design rather than technical reasons. it doesn’t have to be 2-player but it would have to be in a similar spirit.
i am not going to clarify what a 2 player text adventure or IF game would look like, because i do not know. even a game that asks you to have someone sitting next to you the whole time would count.
reducing that to a 2-player game, you’d have something like Sleep is Death, which i guess is pretty close to what this thread is asking for. i still would not describe that as a “text adventure” though.
maybe the key thing here is there are two basic ways you could split this: one player acting as the parser, or both players being, well, players. i’d consider the former more of a collaborative storytelling exercise or a PnP game with a cute narrative frame; the latter is closer in spirit to what i’m thinking of.
There was a 2-player love story if you played online and I can’t for the life of me remember the name. I seem to have neglected to bookmark it.
The homepage had a white background and a picture of a red rose, if I recall correctly?
Also, I never tried any of the multiplayer options in Fallen London, but maybe they work as some sort of limited co-op or competition? Does anyone here play FL?