Andy Robinson. Microsoft has confirmed it's offered Sony the option to put future Call of Duty games on its PlayStation Plus subscription service on day one, as part of its bid to appease regulators' concerns over its proposed Activision Blizzard acquisition.

This is the big question fans keep asking. Call of Duty is one of the biggest-selling video game franchises of all time, ranking behind just Mario, Tetris and Pokemon. The good news for Sony fans is it will be 2038 before it's even possible that the game could be an Xbox exclusive.

Poker is a family of games that exhibit imperfect information, where players do not have full knowledge of past events. Whereas many perfect-information games have been solved (e.g., Connect Four and checkers), no nontrivial imperfect-information game played competitively by humans has previously been solved.

Secondly, the broad set of hidden information of the tiles makes Mahjong a much more difficult imperfect-information game than previously studied ones, such as Texas hold'em poker. Thirdly, the playing rule of Mahjong is much more complicated because of the various actions involved.