Zork isn't obscure. I know of it, so it can't be obscure... ;-)
I like Uplink, I still do. Well okay It's not that obscure but still...
So let's try again...
Rise of the Dragon from Sierra Dynamics. Ha! That's a good one. Does somebody remember that game?
Yessss, the nostalgia is back...
I found it...
Just to quote Wiki at bit:
"[The game] was given a MA-17 rating by the Videogame Rating Council, most likely for profanity, references to a fictional illicit drug, cross-dressing, prostitution and partial female nudity."
It can't get much more obscure than that...