Don't Starve and Don't Starve Together also. Been getting updates for years.

In Roguelikes and Roguelike-adjenct games there are also a few games that get close. (I'd even argue some totally eclipse SV/Terraria in that regard, but that depends on your definition.) Some, but not all, of them are even completely free and open source.

Off the top of my head, a few examples would include Dwarf Fortress, UnReal World and Nethack. Maybe some Space Station 13 servers if you count that too.

If you’re in to that, check out Clan Lord. It’s been running since ‘99 with monthly updates.

Terraria. I wanted to like that game but immediately found it unenjoyable and disagreeable in every way. I'm still waiting for a Stardew Valley-like game that is actually good (i.e., has farming without ridiculous missions like "find the cows and build a pen for them) and doesn't require the player to "craft" his own tools with ridiculously complicated mechanics. I hated "My Time in Portia" for the incredibly difficult crafting, that had no tutorial or explanation and was very poorly conceived.