Hell Let Loose (Steam link) is a multiplayer tactical first-person WW2 shooter developed by Australian studio Black Matter and published by Team17 - the game was initially released after a Kickstart campaign in 2017 before its release on Windows and Xbox. It uses Unreal Engine 4 as well as EAC as an anti-cheat technology, and this makes it currently unplayable on Linux and the Steam Deck, as you can see from ProtonDB:
They just had a series of announcements in a video recording, and one of them is of particular interest to us here. They are working to make the game work on the Steam Deck (which means proper EAC support) by September 2023.
That’s just another game to add to the list of online multiplayer games that work flawlessly on our platform, with other titles being Apex Legends, Predecessor and Multiversus, just to name a few.
Now the question on everyone’s lips is “how did Australian devs get their hands on a Steam Deck since it’s not officially distributed in Australia?” :-)