In these types of games, player does not require to be on-screen while the opponent is playing his/her move. There may or may not be a fixed time for a player to put forward his/her turn. Players get notified via push notification about the opponent’s move.
In these types of games, both the players must be on-screen throughout the gameplay even if the opponent is playing his/ her move. If anyone of the two players goes off-screen, the game gets discontinued and cannot be proceeded further to the same game even if the player comes back on-screen.
For example in Table Tennis, both the players must be on-screen as Table Tennis is a continuous game. One can’t leave the game in between the gameplay. If anyone of the two players goes off-screen, the game gets discontinued and cannot be proceeded further to the same game.
In these types of games, apart from the players there is a dealer(s) who actively monitors/participates in the game. This dealer(s) can be a hosted AI, server generated character, server-side anti- cheat logic or server side authenticator.
For example in Casino Games, apart from the players there is a dealer who distributes the card, manages player turn and allocates the points. These activities of the dealer are maintained by servers and neither of the players are involved in it.
For more details on the development side, you can refer this page.