Borderlands, particularly 2
Dungeons and Dragons. With the right group, you can do anything.
There are other RPGs that may scratch slightly different itches, if the fantasy + combat + resource management parts of DND don’t really appeal.
I really like Fate. it’s a lot more focused on story and is overall a lighter system. it does ask more from the players though.
Left 4 dead 1&2, Halo 1-3 + Reach. Man I miss co op games with friends on split screen. Do modern games even have split screen options outside of Nintendo titles?
+1 for the Bungie Era Halo franchises, IMO they have one of the best stories, and they honestly all hold up well. Plus you have so much that you can burn through with friends, and it has such deep lore you’ll be chatting for hours.
1, 2, 3, ODST, and Reach are all great for this. 1 and 2 support 2 players. 3, ODST, and Reach support 4 players
Baldur’s Gate 3, good for up to four player coop.
Borderlands 1 & 2, too.
I’d suggest Planescape Torment over BG1 or 2 - if you’re willing to work with archaic UIs, Torment is amazing.
Planet crafter.