The Unofficial Squaresoft MUD is a free online text-based fan-game, which is based on the worlds and combat systems of various Squaresoft games. UOSSMUD includes a class system based primarily on Final Fantasy Tactics, and worlds based on Chrono Trigger, Secret of Mana, and Final Fantasy 5, 6, and 7. It has a focus on accurately recreating these worlds from the original games and mirroring their storylines in missions.

In addition to the above, UOSSMUD also has smaller amounts of content from a wide variety of Squaresoft and Square Enix games. There are classes based on the combat system from SaGa Frontier, bosses from Xenogears, and a roguelike mode based on Chocobo's Mysterious Dungeon. This is a MUD with fast-paced combat, and a multiclassing system that allows for a wide variety of strategies.

UOSSMUD has a blind user mode available to improve the experience for those who use a screen reader to play.