true
'''MUF''' (Multi-User Forth) is the Forth-like programming language invented in 1990 for multi-user role playing system TinyMUCK. Each MUF program can access and manipulate in-game objects (items, locations, exits, players, programs). MUF programs can be invoked through global or local aliases or executed when an in-game object is examined or otherwise manipulated. The concept of user-programmable virtual world was later reimplemented with programming language LSL in the MMO game Second Life.