Some video games that would make good additions. But mostly Postal Dude as a killer.
Postal 2: The Postal Dude as a killer. It would be fun, and Postal fans are already semi-adjusted to playing in the same way as this game. Also, I think it could be an interesting addition to the community too, seeing as there's probably overlap anyway. And there is incredible perk and skin potential, for example the perks could be based off of community in-jokes, like denying Postal 3, which could mean that one hook is invisible to the Dude because it's the "third" one. If you would like to switch perspectives for a killer, you could even be weird and style him off Postal 1 and make his perspective top-down or something. Skins could be based off of the other games, including the girl variant of the character. And if they need a ranged weapon, why not go with scissors that make them run, huh?
Portal. Now, I know any Valve game would do, but Chell as a Survivor would be a useful character, and I think could fit well in the game. Also it would be interesting to see if you can get her voice actress to show up. Her voice lines are very well done. (This is a joke, she is obviously mute.) The main mechanics for this are already available for killers, honestly, this could just be a skin, but I think it's more interesting to see Chell get killed by a Demogorgon or The Pig than, say, Gordon or Alyx from Half-Life. You just expect it to happen with those two.
Now this is a really odd one, but the map from The Witness could make a good map. It's a puzzle game, and you match the environment to lines, or use line based puzzle screens. Honestly, that can just be a killer even without the actual murder. But yeah, fulfilling the lines makes these magical wisp things and those can change elements of the world. There are also wires everywhere. I was thinking about this recently and still think it's a good one.
The Monkey Island games. I know it won't happen, even though I think the rights are owned by the creator now, I still can dream, can't I?
Doki Doki Literature Club. Look, all you need to do is politely ask Dan Salvato. Rights aren't even that hard. Please. Pretty please?
The Stanley Parable. Stanley and his bucket. But Stanley should be a Survivor. The Bucket... I don't want to think about the horrors that the Reassurance Bucket would do... Also, one of Stanley's perks could be the Stanley Parable Adventure Line that leads to an unjammed generator.
There's this game called Bioshock that could be a nice addition. It got a good reception. There's a good argument for including it in this game. Would you kindly consider it for approval along with the others on this list?
A Tattletail skin for the Ghost Face or The Good Guy. Because who doesn't want to be killed by an evil Furby? Although this could be a killer in it's own right. With a mix of collecting batteries for the torches, which could generate for people who don't have them and stealth on the killer's side.
Anyway, have a nice day. Enjoy the suggestions. Please consider at least one. I'd prefer more than one, but I can do with one. Preferably a fun one.