I played a very long-term campaign with some of my friends from college. I think the campaign lasted 3 or 4 years. The system was AD&D 2nd Edition, and we were all elves of some stripe. In fact, we were all elves using the Complete Book of Elves which isn’t all that overpowered if you are all playing elves using kits and options from that same book. (Otherwise, it’s ridiculous.)
Anyway, we had a drow wizard-cleric, a high elf ranger, a high elf fighter (specialist in great bow archery), a high elf fighter-thief, and my character, a grey elf bladesinger (so serious!).
Our game was set in Greyhawk, which remains one of my favorite settings because it’s so basic and "high fantasy" without being too much more than what it is (unlike Forgotten Realms, which tries too hard to have everything jammed into one world). We went through the Temple of Elemental Evil, and all the way through the Slavers of Freeport series, into the Underdark, the Spider Queen, and finally slaying Lolth. I think we were in the mid-teens for levels at that point, though the fucking drow was always a level above us (DM’s wife privilege.)
We also made a set of "alts" for when we needed a bit more levity. When 2nd edition started giving way to 3rd, we updated our alts to try out the "Skills and Powers" transitional stuff from 2nd ed (I’ll bet you’d forgotten that bit of D&D history, eh?) and eventually played a couple of sessions with 3rd edition characters who were descended from or otherwise related to our main heroes.
I wrote scads of game-fic for this campaign, and drew quite a bit of art, although the above piece is not mine (the fighter-thief’s player was quite talented). I credit my character with helping my mind heal from some very significant trauma in my life– when I had nightmares at night, she would show up in my dreams, and I’d draw my sword and do battle with whatever foes were tormenting me.
Eventually, the game ended. Not because of edition wars, but because of divorce. It was a long campaign, fraught with drama (some in-game, some out), and the kind of experience that you either adored (I adored it) or hated (my husband played for 3 sessions and hated it).