I'm a ridiculous sucker for mech-action games and RIG Riot just landed on my radar. A roguelike third-person mech-action shooter with some fun looking combat.
Developer starlit studio recently put up a Linux demo for Solace Creek, a retro-styled horror game that has a focus on suspense, exploration, stealth & puzzles.
Valve released a fresh update to Proton Experimental for August 28th, bringing plenty of improvements for Windows games on Linux / SteamOS and Steam Deck.
Metal Gear Solid Delta: Snake Eater from KONAMI is a remake of the 2004 game METAL GEAR SOLID 3: SNAKE EATER. It's out now but it's Steam Deck Unsupported.