Just a quick bugfix as it took me a while to find a resolution to this issue.

If you're trying to play a game on Pop!_OS 24.04 (which I'm really liking, by the way!) and are finding the mouse is going all kinds of wacky in games launched by Steam, you might find your problems go away if you put the 60-steam-input.rules file (which can be found on the official Valve git repository) into the following directory: /etc/udev/rules.d/, then rebooting!

I've been working through my video game backlog for years now, and I'm currently playing through Dishonored. I'd just reached the final level when I foolishly decided it'd be a good idea to upgrade to the newest Pop!_OS release. The upgrade went fine, but launching the game after went... a bit wild. First the keyboard didn't work and the mouse was funky, but disabling controller support in the games properties on Steam fixed the keyboard. The mouse thing... yeah that took a while. Whenever I moved the mouse even a tiny amount, my view would spin down and to the left very rapidly. I'd spin around in a circle, what... a dozen times? More? I couldn't look up, I couldn't look right. Even on the slowest mouse speed barely made a difference!

To fix this I was watching dmesg, fiddling with mouse smoothing, trying various Launch Options in Steam, mucking about with the resolution and sensitivity of my mouse with Piper (which is cool! I didn't know this existed before this problem... silver lining and all that, eh?) and poking at the fact that my mouse - a Logitech G502 - was also reporting itself as a keyboard because that had seemingly caused problems a few years ago (it turns out needs to do for the macro support)... When I stumbled across a little reddit thread from 9 months ago with this fix. Full props to them!

Hopefully posting this helps some out there to avoid digging and searching the 'net for four hours to unravel the fix...