Sorry, for me the program starts, I see some green (spiders) and then after like 3 seconds, they all disappear.

Locoweed. You should have read the description above.... the green dots are waypoints. and you have to press space to create 1000 spiders.

Okay blink here is my ooooold project folder.
*Click*
Beware the ugly code might bite.
BTW: I decided to make a handy script pack as a contribution including an octree solution for entities, my swarm behavior script, a special spider movement script (walk on walls no matter what the normal is) and some collision avoiding stuff.
It should be easy to convert some of those scripts to c-script without going through too much trouble.

Thanks, it would be great practice, studying scripts for me.

Real nice work man, keep up with that, you already pwned starship troopers(2005) with only 300 bugs. Because some projects need quantity above all else.