I think you will be relieved at how easy it is. A lot of games are flawless on Deck without the developers even targetting Deck or linux at all, since Proton has gotten so good. Here’s Valve’s guideance: https://steamcommunity.com/groups/steamworks/announcements/detail/3001070242218057029

I also miss the gritty, dark, isolated atmosphere that KF1 had. I still had my fun with KF2, but when they introduced robot enemies, sci-fi weapons, and generally goofier cosmetics, it killed some of what made the games feel special

!2007scape@lemmy.world. RuneLite works fantastically.

RuneLite is linux native though. If you want something specifically through Wine, others have said Guild Wars 2 and FFXIV, but I’ve also heard good stuff about STAR WARS: The Old Republic. And if you’re okay with something a little more obscure/“out there”, Shakes and Fidget has great reviews (it’s a satire on MMORPGs).