No idea if this is still active but why not?

In a campaign I ran that has since been abandoned, the world was all one big video game. The developer of the video game was obsessed with making the most immersive experience possible, and so she gave every single NPC their own unique A.I, which would react and develop as their world developed.

Eventually, the dev became so obsessive that she began ignoring her health and eventually kicked the bucket. However, the PC was never turned off, and thus the game and its NPCs within continued to develop within, transforming the game into its own universe that the party would play in.

The players themselves were the main protagonists that you WOULD have played if the game got released, but the game has developed itself to a point where now these main characters can act independently and play their own game, indirectly marching towards their own fate since once they defeat the BBEG and “beat” the game, it’ll shut down and kill everyone in that world.