Mindustry is really well made computer game that I enjoyed playing a lot. It is Free Software.
Here are two guides to get a deeper idea about details of the game:
- Steam Community :: Guide :: Deeper Understanding of Mindustry I - Transportation
- Steam Community :: Guide :: Deeper Understanding of Mindustry II - Extraction and Production
r/Mindustry - How unattended sector defense works (most effective turrets and such) is a useful explanation I found of what happens in Mindustry 6 when I leave a sector to itself.
And #959466 is the RFP (wink, wink!)