You want to spawn 1000 NPCs quickly. But you don't know how.

*Start Gmod and go into a Singleplayer world.

*Press Q and go to the ''NPCs'' section, and click on it.

*Go to the ''Humans + Resistance tab and click on it.

*Choose any NPC, and click rapidly around you to spawn them.

*If your quick, you'll get the achievement in about 5 minutes, and the achievement should be called "Procreator."

So this is how you spawn 1000 NPCs quickly.