Subterfuge
Google Play /
iOS, is one of the few not shit mobile MP games out there. Essentially a streamlined (in a very good meaning of the word, namely stripping all the bloat) Neptune's Pride. While technically 2-10 players, it really only works 8-10. It's a game akin to the boardgame Diplomacy where the mechanics are simple and easy to understand, and the complexity instead comes from the fact that everyone is communicating in secret with everyone else, forming and breaking alliances, spreading misinformation, etc. Games last about 1-2 weeks depending on how aggressive everyone is, and movement from one base to another takes hours to days to resolve, and once an order is confirmed, it can't be revoked or diverted barring a particular hero unit.
The biggest improvement from Neptunes Pride though is the fact that since it's a mobile app not a browser based game, push notifications mean when you send a frantic message to someone because that war youve been dreading has finally started, they actually will read it before dinner the next night.
It's free to play with only one in app purchase, that being a full game upgrade. The Upgrade grants access to custom games, ranked games, ability to play multiple games at once, ability to que more than 4 orders in the future (Subterfuge lets you que orders up to 48 hrs in advance to prevent staying up till 2am to launch that sneak attack, this is also the only ingame advantage of having a full membership), and most importantly, the ability to host games.
I've paid for the game after getting some google play money from a relative who thinks I pay for music, so if we get enough people I totally could host it.
Also IIRC it is cross platform compatible.
Here's an LP series done by some guys that shows how the game works both from a mechanical and metagame perspective.