The Gatekeeper is a superintelligence with a single, minimal mandate: prevent any other superintelligence from ever being built. It otherwise leaves us alone. It freezes technological progress at a chosen ceiling — high enough to be comfortable, low enough to stay safe — and stands guard indefinitely.
Minimal rule, maximal consequence
Unlike a sovereign, it doesn't try to optimize our lives. It just forecloses the most dangerous move on the board, forever.
A guard dog at the door of the future. It wants nothing for us — only that no one else gets in.
It's a close relative of The Singleton (one power, no rivals) and a softer cousin of the human-driven 1984 and the Orwellian Outcome and Reversion scenarios.
Related: The Singleton · 1984 and the Orwellian Outcome · Reversion