When Reversi is opened, it displays a screen that allows you to configure a new game and to launch it.

This screen notably allows to select if you want to play Classic Reversi or Reverse Reversi, to choose if you are going to play against the computer or with another player, and in the former case to change the computer level.

If you are opening the application for the first time, Reversi defaults on an easy Classic Reversi against the computer. Else, it will have remembered you previous settings.

For launching a game from here, just click on the Start Game button. A game can also be launched with the ShiftCtrlN keyboard shortcut.

Once a game has been launched, you can always go back to this screen by clicking on the New Game button, or using the CtrlN keyboard shortcut.