Can you name a game that is older than NetHack and still in active development? I can't.

Wikipedia's historical list of MUDs ( https://en.wikipedia.org/wiki/List_of_MUDs ) suggests that MUD1 (1978, homepage: https://www.british-legends.com/CMS/ ) and MUD2 (1985, homepage: https://www.mud2.com/CMS/index.php ) might still be active. From what I can tell their codebases are pretty light on substantial updates in recent years, but then again Nethack was at point considered abandoned for about a decade.

	▲	anthk 6 hours ago \| parent [-]
		You forgot the forks like Slashem and the like, which were born from Nethack 3.4.3.

You don't have to look very far.

> Stable release 5.7.15 / 4 June 2021; 4 years ago