When you find yourself trying to remember a show (or any works) that's on the tip of your tongue but just out of reach, come here - the collective brain of the TVTropes community can probably help. Post all the details you can remember (examples help). If you're looking for a trope, head over to Trope Finder. Have general questions about tropes? Visit Ask The Tropers!
Sounds a lot like Rope. https://en.wikipedia.org/wiki/Rope_(play)
I've only seen the Alfred Hitchcock movie, and I don't remember anyone other than the invited guest dying, but other than that it sounds similar, maybe an adaptation?
Edited by CodricI agree that it sounds a lot like Rope - the Wikipedia entry for Rope mentions R.S.V.P. as a film that "borrowed several key elements from Rope" and was made in 2002. https://www.imdb.com/title/tt0271210/?ref_=fn_al_tt_2
Sounds very similar to 'The Last Supper', which starred a pre-superstar Cameron Diaz and was made in 1995, released in '96.
https://tvtropes.org/pmwiki/pmwiki.php/Film/TheLastSupper
https://www.imdb.com/title/tt0113613

1) It was about a group of college students having a dinner party. They discussed morality and I think specifically the ethics of murder. They've either invited a guest or a stranger turns up and they decide to kill him, but most or all of them end up dead instead.
2) It shot for deep and ended up just pretentious and confusing, particularly the ending.
3) It was very low budget - all taking place in one house and I think most of it in a single set.
4) It was short - I think around the 75 minute mark, certainly less than 90.
5) At least two and possibly more of the actors playing the students went on to bigger things but weren't famous yet when they made it. I saw it in about 2004, which I guess makes it a late 90s or early 2000s film. (I really thought Josh Jackson and Elijah Wood were in it, but I've checked IM Db and it seems like it wasn't either of them.)
6) It had a short title, probably just a single word.
Solved! Thanks everyone. Turns out I'd turned The Last Supper and Taboo into a single film in my head.
Edited by Carmilla