Xzbeat on 16 March 2016
Forget Minecraft, forget Wii Sports, forget GTA V, Candy Crush or any of the other pretenders.
With an estimated 1 billion unique people who have played the game then Solitaire must surely be the all-time champion!
Also, there are now multiple mobile versions of the game that have more than 500 million downloads between them:
https://play.google.com/store/apps/details?id=com.eternusgames.solitaire
