Early in the 21st Century, THE TYRELL CORPORATION advanced Robot evolution into the NEXUS phase — a being virtually identical to a human — known as a Replicant.

The NEXUS 6 Replicants were superior in strength and agility, and at least equal in intelligence, to the genetic engineers who created them.

Replicants were used off-world as slave labor, in the hazardous exploration and colonization of other planets.

After a bloody mutiny by a NEXUS 6 combat team in an off-world colony, replicants were declared illegal on earth — under penalty of death.

Special police squads — BLADE RUNNER UNITS — had orders to shoot to kill, upon detection, any trespassing Replicant.

This was not called execution.

It was called retirement.