Reversi for Android consists of a reversi engine and a GUI. The application accepts moves through the touch screen, the trackball, or through the keyboard. An optional \move coach\ shows all valid moves as ghost stones and animation highlights the new and flipped stones after each engine move. Full game navigation enables users to correct mistakes or analyze games. Games export to the clipboard or via sharing. The engine plays at various levels (including random and free-play). The user can play either side. The application connects to an external electronic reversi board (Certabo). Online manual at: https://www.aartbik.com/android_manual.php