Subverted Matrix style MU*
I've always thought another way to write the Matrix would be to set it post apocalyptic, where the humans were willingly in stasis pods beneath the Earth, in a virtual reality society. Humans not in the stasis chambers would be the police, and would insert into the virtual reality world to hunt rogue programs (ala the Agents, the Voyager episode with 'Fear', the other weird things), renegade hackers into the virtual reality world (something like pirates), or people inside the virtual reality subverting it from within (Cypher). It would be sort of a meta-MUSH.
I always wanted to write a story where a large portion of the population is inserted into VR and must perform for 'points' in various worlds such as 'Medieval' or the like while the rich enjoy and vote on their favorite actors. When you die, your memory of your previous character is purged and you can use your points to buy advantages for your next character, or improve your out-of-stasis-pod life, or buy a better 'job', such as moving up from dickwasher to janitor or something.
That would probably work pretty well in a MU*, I suppose.
@Chet That is very Eclipse Phase. Most humans are now digital uploads of their brains living in VR
Like Westworld, but with everything being virtual.
There actually was a Matrix mush for a while, but I think it may have gotten shut down on a copyright infringement.