Tonpuusen, literally 'east wind game', is the short format of riichi mahjong: play ends when the East round finishes. In the standard sequence that means four hands (East 1 through East 4), with each player taking the dealer seat once. The name joins the kanji 東 (East) and 風 (wind), the character used for the round wind.
East keeps the deal after winning or after being tenpai at an exhaustive draw, so the round can run past four hands. The honba counter rises after every East win and every exhaustive draw; it changes the payments in the next hand.
The shorter format offers fewer base hands in which to change placement than a hanchan. The correct aggression still depends on the gap, seat, hand value and risk; game length alone does not require pushing from the start.