It's good. Not like many other games. Army builder/turned-based strategy map domination sorta.
http://store.steampowered.com/app/403950/3 is available for droid now I believe. 4 is just 3 with better/more features.
I played 346 hours in 3, and have already put 147 into 4, which has only been out since Nov 16, 2015
If anyone wants more details on how to play, or what it is like I'd probably be willing to write up a guide type thing,
since it has some learning curve, being not like many other games,
and looking sort of strange/gimp at first glance.