Issue not necessarily appearing on the Steam Deck but it would benefit from it as well - better handling of mixed input from a controller and mouse. I have a Steam Controller and prefer to have it simulate a controller in FPS games but to have the right touchpad work as a virtual mouse to ignore in-game acceleration curves and deadzones.

Some games handle it well, like Cyberpunk 2077, some games like Grounded tend to show keyboard prompts whenever it would detect mouse input but still function correctly. If I’m not mistaken Borderlands 2 would drop it’s UI controller layout whenever a mouse input was detected, which can probably be skipped by using layout switching/overrides from Steam Input. The worst offender so far is Hunt Showdown, where the game freezes for 0.5 s when it detects mouse input, even if it’s a physical mouse input.

All of my testing has been conducted on Linux, not sure how it behaves on Windows

I would just like to see more games be a bit friendlier with settings. Give me some real potato settings or focus a bit more on optimization so I can play stuff without having to futz with settings so much.

Stellaris isn’t awful on deck, but it would be nice to have the console controller layout that ships with the XBox edition.

Mostly my problems with Steam OS (and windows Big Picture Mode) is the seeming lack of options for controllers that aren’t Xbox or steam controllers. Steam used to be excellent at this but more recently in Windows 11 (and in Steam OS) the controller support is great when it works but if you want a more granular experience it’s just not there). I somehow have less settings and options for controllers support than I did in Windows 10, and the way it detects controllers cannot seemingly be changed. So if you’re like me and own an SN 30 Pro2 controller with back paddles, you can’t configure them without jumping through a whole lot of hoops. And in game that means that you’re just not going to be able to use them which is a minor inconvenience but one that’s been bugging me.

Workers and Resources keeps crashing and has no usable audio.

Cataclysm: Dark Days Ahead has impossible controls as it uses a full-size keyboard normally.

Minecraft/Minetest need optional gamepad control, especially GUI-wise.

Firefox and streaming is awful on the Steam Deck.