The Big Tuna

From the introduction:

This is a GMless game where all but one of the players are Max Tuna. To be more precise they are all part of the Big Tuna’s Brain. The other player is the bad guy and represents everyone else. The game consists of the players running Tuna through a series of acts. They get to say how he deals with the challenges put forward by the script and the bad guy

User summary:

The game progress is scripted. Play involves collaborative narrative construction around the scripted events.

Note an earlier implementation of this rules set was developed under the title "Bond's Brain", by the same (unknown) designer.