I want to go into this point:
4) As an expansion for fans/programmers you can add an option to program the behavior of robots. (Well, I get some ideas from games Battle Snakes and Grobots) What you can add is:
a) make robots moduled like armor
b) add option to have some proportion of robots: I want to always have 5 ranged for 3 melee robots
c) add strategies: I want to have 5 robots defending my base and 5 attacking enemy base.
d) add more complex strategies: I want to specify gathering points, patrol regions, attack regions. That should be maintainable: I want to have 5 robots patrolling this region. If one is destroyed another one should replace it automatically. I know this base if heavy defence, I want robots to attack in packs of no less than 10 ranged, 5 melee.
To a) this is a point I'm thinking currently, but not from that aspect, more from how could I built this. Because what I miss in this game is something like the robots factory in Star Wars. A production street, which has a pulsed production cycle. You need to put the right items into it in the right time. But the idea is not finished yet.
To b-d) this is not the way, how factorio works. It is a physic simulation. That means, the way it can work is not
to have some requester, where I can adjust what I want. The way it works is to make some physical change in the game.
In this case: measure, compute, react. A sensor checks how many bots are in an area. If it is too low it will fire a signal, which let the bot-production run, until satisfied.