NetHack - This 38-year-old game keeps outsmarting me and I love it
Summary
NetHack, released in 1987, remains surprisingly vibrant due to its coherent system design and active maintenance by the DevTeam. The game features early multiplayer concepts, persistent grave/loot behavior, and a codebase built in C that is still buildable from tarballs on modern systems, with MoMA recognizing its cultural significance.