This app was mentioned in 1 comment, with an average of 1.00 upvote
Galcon Fusion is a deceptively simple RTS game. Lots of different game modes, short rounds for short trips, only downside is it's not the prettiest, but it runs on anything and it runs well.
https://play.google.com/store/apps/details?id=com.galcon.fusion&hl=en