This app was mentioned in 7 comments, with an average of 1.43 upvotes
I don't know Vietnam 65, but
> turn based strategy game with simple mechanics
Makes me think of Great Big War Game, Great Little War Game, and UniWar.
Sorry I got the name sightly wrong. This is the game I meant though- https://play.google.com/store/apps/details?id=com.rubicon.dev.gbwg