Mahjong Tengokuhai is an android based game client produced by Hangame.
The service is free-to-play. However, players must have in-game currency in the form of "G" in order to play. Periodically, players receive amounts of 50,000 G in their inboxes. With that, players can enter the game lobbies to earn more. In a sense, this is tantamount to mahjong gambling. As an extension, players may actually spend money to purchase set amounts of G.
The game lobby is generally split into two main areas: Sashiuma and Online. In both areas, players wage their G in accordance to different rates per 1000 points.
Sashiuma features 1-on-1 play. Players are across from each other, while two computers are to the left and right. In all sessions, one of the computer players is the dealer. Instead of point exchanges, players who win the hand gain G and have the option to continue play with the next hand or not. In essence, the game functions like iikyokusen.