According to a Microsoft employee solitaire is the most used program in Windows. In fact there was a developer specifically dedicated to updating it for Microsoft Vista. It was originally included into Windows to "soothe people intimidated by the operating system" and to teach mouse skills to the uninitiated.
Microsoft's usability research crew discovered that the three most-played computer games (solitaire or something else, Microsoft or otherwise, preloaded or user-installed) are, in order … Spider Solitaire, Klondike Solitaire, and FreeCell.
So which is it? Which game is the one you choose when you want a little "mental break"?