ℕ𝕖𝕞𝕠

I hardly think a game under development is off-topic in a gamedev muni

Multi-User Dungeon (or Delusion, or Dimension)

Precursor to MMOs, they were always-on shared worlds you connected to over the Internet. Most were text-only and accessible by telnet, some had web clients or downloadable dedicated clients; some had static images as backgrounds or mob icons. It’s also the origin of the word “mob” to mean videogame enemy, as MUDs pioneered MOBile enemies that could follow you from location to location or wander around on their own.