Gatekeeper is an early videogame created by an ancient alien civilization, for a system called the Brain Embryo. From the Constellation Database of Electronic Games of a Certain Complexity:
The Gatekeeper, a minor figure in the Consensus Mythos, manages traffic between the land of the living and the land of the dead. In this game you adopt the Gatekeeper's dull task indefinitely. Due to its simplicity, a game mostly of theoretical interest to ludologists.
We hope you enjoy this remake.
(Reading Constellation Games may improve your enjoyment of this game, and also of life in general.)