I'm putting together a bunch of one off and short game ideas for the group I play with IRL. Everyone who plays is up for a Game of Thrones setting, but I think that Dungeons and Dragons rules miss the fatality of GoT. I'm also interested in doing a film noir setting, hard boiled detective stuff. In either case, death would be permanent (or usually so) and getting stabbed or shot would often prove fatal.

Are there any variant rules for a "hardcore" mode of D&D? I know HP serves a purpose but I think a little gory realism would work well sometimes.

I don't know if there are any existing rules like what you are looking for... But something that you could do is run it more like the game Traveller.

Instead of taking hits from HP you take hits to your physical attributes (Str. Dex. Con.) When your attributes are reduced to 0 you are dead.

This makes it more like real life, to signify blood loss, and/or the lack of use of wounded limbs, etc.

http://hyboria.xoth.net/index.htm


That site links you to a D20 setting for the Conan movies.
You're going to want to navigate to here, the "Die, Stygian Jackal!" alternate rules. It's a rule set that I've been dying to use for a long time (along with a few other alternate things for a total home brew game)that is really just the grittiest, deadlist system I've seen.

http://hyboria.xoth.net/rules/die_stygian_jackal.htm

I've personally put a few spins on it but this is the basis for something that I think you're going to like.

I made a D20 variant that simply takes out HP. Your saving throws are what keep you alive. Fail, and you die. Makes for an interesting, quick paced game. The great thing is, you can level up a lot, and it matters for skills and techniques, but the truth of the matter is a level 1 character can still kill a level 20. Not that anyone ever made it that far...

There is a variant in unearted arcana where you have a pool of "endurance" and then one for "hp" where if I remember correctly endurance is like you normally would do HP but your "HP" is just your constitution score.

Normally if you get hit you take it off your endurance first, and then when that's done it goes off your HP, but if you get hit with a crit it skips the doubling or whatever and goes straight off your HP.

Didn't explain this overly well because it's 7am, but basically it means if someone crits you, you're almost certainly dead. Kinda provides that one wrong move you die feel.

Thanks guys, I will be taking all of this into consideration. The Jackal one seems the best thought-out but also the most complicated. I'm going to brainstorm with my IRLs and let you know what I come up with.