Sonic X Shadow Generations has passed three million copies sold worldwide, Sega announced through the official Sonic account on 26 October, two years after the game first launched.

Three million copies, with no platform split
The post thanks players for the milestone but gives no breakdown by platform or region, so the best-selling version cannot be identified from it. The figure counts copies sold, not people playing today.
The package bundles an enhanced version of Sonic Generations with a separate Shadow campaign built around his own abilities and levels. The total therefore belongs to the whole product, not to the Shadow campaign on its own or to any add-on bought separately.
Players still deciding can read our review of Sonic X Shadow Generations for the experience itself. A sales number shows reach; it does not say whether the game suits a particular player.