"Invader Script" is Navigation AI for hostile ships.
This guide show how to make new Invader.
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=316380987
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=325188253&tscn=1417818156

Related works:
http://psteamcommunity.yuanyoumao.com/workshop/filedetails/?id=317385183

Create your ship. Invader ship need turrets to attack. If you want small ship Invader, you need some of MOD. I used Small Ship Mega Mod Pack for Invader Fighters. Of cause other turrets can be selected as you like.
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=305329302

Change Ship name as "-Invader". This is a keyword to identify the ship to navigate.

If you forgot to change ship name, you can do it after export.

Don't forget supply ammunition and uranium.

Make your Invader ship as Cargo Ship.
see the Guide:http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=326136221

Select MODs.

• Invader Script. "Kill Counter" option can be selected.
  
• Your Cargo Ship. "InvaderRed" in the picture.
  
• Blocks you used in your ship.
  
• I selected CargoshipRush MOD in the picture. this is option.

Don't forget to enable cargo ships.

Note:

• Invaders have "Sensor Range". If you are enough far from Invaders, they can't find you.
  
• Invaders will be banished by time. Because they are Cargo Ship.

Now war is beginning!
If you selected Kill Counter, Numbers of Existing and Killed Invader are shown.