Uno was one of the major success stories of the early days of the Xbox Live Arcade service on the Xbox 360. With a combination of good release timing, the right price and a game that people either already knew how to play or could pick up quickly, it wasn't surprising that Uno was the first Xbox Live Arcade game to top a million units. With continued support through card content packs and additional Avatar and Xbox Vision Camera support, Uno continues to be the #1 best-selling game on the service. 4/5