Very nice tutorial tuschcarsten,

Very well documented, simple, and fun.

I did manage to get an illegal arguments error in bullet_event() : ent_playsound(my,hit,2000); when I shot alot of bullets rapidly at a target and it died. You should probably make it
if(my)
{
ent_playsound(my,hit,2000);
}
or something, not really sure, but I imagine that the event is already started before MY is removed from the previous bullet and then by the time it get's to that line of code the MY is gone causing the error.

I would recommend this tutorial to any novices who are trying to start learning about AI.

Good stuff,
Loco