For Mobile, my favorite is the Age of Strategy series, there is also a Fantasy and Galaxy edition with different themes and units etc...
It's a free turn based tactical game with persistent rewards and new units and cosmetics to earn through in-game activities. The Multi-player is a little rough wound the edges, but its highly customizable and has years of community behind it.
There are enough unlockable units that your army is likely different from another players, like a skill tree style progression. I really love it, thought id share the name since I never see it mentioned on forums. I prefer supporting smaller development teams, and this developer has updated through the years faithfully
Hope this helps,
a fellow kerbal-fan
