I have tried all these on Linux through proton.

Dusk - the OG boomer shooter revival game, should be the first game to try to see if you like these kinds of fps.

Amid evil - beautiful looking FPS instead of firing guns you fire unique magical weapons.

Ultrakill - extremely difficult movement shooter with a very interesting setting and lore. Its still not fully complete theres like a final layer thats still cooking but what's there is worth experiencing.

Selaco - FEAR inspired FPS built in GZDoom somehow. Tight movement, great gunplay, interesting enemy difficulty progression, superior AI that will flank your ass and hammer you with what feels like tactical actions, great interactive environments.

Turbo ultrakill- one of the most fun and bombastic FPS ive ever played. Play as a merc who gets turned into a living chainsaw as you ruin the plans of wannabe trancendent techno gods and run away super AI one bullet at a time

Cultic - plays heavy into blood and residents evil 4 inspirations to deliver a very mood atmospheric FPS with the best goddamn dynamite throwing mechanics since OG Blood itself. The single dev is really passionate and is constantly sharing updates to episode 2.

Ion Fury + ion fury aftershock A love letter to the best parts of build engine games of the 90s. Its incredibly well made build engine game with huge sprawling enviroments and too many secrets. The pistol with auto-lockon is hands down the best pistol Ive every used in any game. Aftershock DLC is even better than the base game.

Zortch - another passion project made by one person with an in-house engine coded just for the game. The enemy AI moves around a lot and the cartoony graphics and plot make it more of a light hearted title to have fun with like a game you would find on the N64. Its only 5$ and easily worth it.