Project Borealis is playable on the Steam Deck but compromises need to be made. To run at 30fps with 80% screen resolution at 720p I had to reduce texture, effects and shadow quality. Other settings for antialiasing, reflections and draw distance were set to their lowest values. I tried FSR but that only made the screen flicker, and the game wouldn't run without Proton Experimental selected. However after all that I was able to play the game and it does indeed feel just like Half Life. Perhaps future updates will improve performance.