Here’s my beginner guide to Rearth’s excellent NPCs. It’s mostly just what’s in his Description, but it looks like we all need it laid out as simply as possible!

1. Build the NPC controller
-- a. It only has one access console and one inventory port so place it well
-- b. At time of writing it doesn't need to be powered to function.
-- c. Build controller with some space around it to allow the NPCs to pop out of the ether. If there are walls etc within a couple of blocks there may be a glitch – not sure. I've seen NPCs pop out from UNDER the controller or from the top, or walk in from the field.

2. Get one or more contract tokens
It looks like these contract tokens are a special invention of Mt Rearth. So you may not find a mention of them elsewhere.

--a. In Survival mode: at the Trade Station, in the Store. You can find this from the coordinates on the datapad you find in your suit inventory when you spawn. Getting there is usually an adventure early on in Survival, and paying the exorbitant price will be impossible until you’ve built some things to trade with or found a LOT of space credits. When I went to the trade post a contract was over SC.200,000. Start saving! Note that the contracts may not always be available – I don’t know the algorithm used – if you can’t see one in the ‘Buy’ list right away, come back later.

--b. In Creative mode: Hit Shift-F10, scroll down to the contract you want, and spawn (directly into the NPC controller inventory if you choose). Try spawning them into the open in front of you - nearest thing I've seen to a harmless black hole!

3. Choose the new NPC’s movement mode in the controller console – Guard, Patrol, Attack…

4. Record guard points if necessary – click ‘record points’ then close the console, walk to each point, and click shift-U. When finished, go back to the block and click ‘end recording’.

5. Select ‘Spawn NPC’ – stand back and watch him go. I think you can do steps 4 & 5 in reverse order. Repeat step 4 to change their orders.

6. Note there’s a limit on the number of NPCs per controller block.

7. It looks to me like all the NPCs spawned from a controller block will follow the same instructions and the same waypoints. You may need to build multiple controllers to get squads that follow a variety of orders.

If something doesn’t work, read Rearth’s Description again and see all the Discussions. If you’re still stuck, you could post here and maybe someone with more experience than I have will help. The above guide is about all I know so far!

Note - I tried setting up a firefight between two groups of NPCs in factions that were at war with each other, but nobody fired a shot. They didn't even shoot at wolves, although they did follow a wolf. The wolf was puzzled and could not eat them. :D

Later the NPCs exchanged fire for a while, but I don't know what made the difference. They are like children - easily confused.