This app was mentioned in 3 comments, with an average of 2.67 upvotes
Check out -
-Legends of Callasia (really good game, tutorials and some MP maps are free, $15 to unlock full game)
-Buccaneers Bounty and Boom (I have not played this game and it is relatively new, similarly free to get into, one time $12 to unlock full I believe)
-Conquest! (I could not quite figure it out but it seemed like a good game, free, has iap or not idk, but might not be so p2w.)
-Age of Fantasy (Zerro p2w, gems are easy to get or throw the dev a couple of bones, limited things to spend gems on)
-Many more that are digital board games. Look at Twilight Struggle, one of the highest rated games of all time. I don't know how active the MP is.
Edit: proper link for Conquest! https://play.google.com/store/apps/details?id=com.GreenLionGaming.Conquest Linkme: Legends of Callasia, Buccaneers Bounty and Boom, Conquest!, Age of Fantasy, Twilight Struggle
I recently stumbled across a 100 % free indie strategy game Conquest!. It's a bit tough to get into, but it's a fun small game where you compete against other players. I recommend checking out the official discord for some little guides to get started.
https://play.google.com/store/apps/details?id=com.GreenLionGaming.Conquest
Other than that you could give Super Auto Pets a try. It has no ads and is a surprisingly deep auto battler against other players. Very good game.
Lots of things come to mind, Blight of the Imortals, Age of Conquest IV, Ascension, Star Realms, Ticket to Ride (on sale), Terra Mystica.
But the only thing that comes to mind that is long term like you say is Conquest!
https://play.google.com/store/apps/details?id=com.GreenLionGaming.Conquest