Play-by-mail games have many different names in French. In the case of Tye 2 and 3 they could also be called browser games or php games.
What is essential, in our opinion in this type of game is that they are turn-based, and players can play from anywhere. There is no need to bring the players together in the same place or even at the same time. Each player prepares his/her strategy, writes numerous diplomatic messages and mails orders on the web site by completing a form before the deadline of the round.
Next the Game Masters (GM) resolves the turn, often using a computer program and sends the debriefing of the round to the players. The debriefing includes public events, which is the best place to add some atmosphere to the game, and the result of private actions for each player individually.
For now our series of 1-2-3 Tye games were and are mainly focused on diplomacy games. The pace was slow, one turn per week since the diplomatic exchanges, role-play and diplomatic agreements take some time to take form. Similarly it often takes a while to develop each player his/her strategy for the next round. 3 hours was therefore easily necessary to give ones orders in Tye 3.
Wikipedia on play by mail