Morrowind for me, Just Good Morrowind runs pretty well on the deck, openmw does support controller pretty well (similar to the Xbox morrowind if anyone else rembers playing that), but I use a community config that works really well.

Restarted my last run because there were a bunch of mod changes between then and now. Found my oblivion disks cleaning up this year so super tempted to get that going as well, would like some qol mods though.

Anyone have recommendations for Skyrim on the deck? Found it chugs a bit with the default settings.