Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

Two-time defense secretary, White House chief of staff, pharmaceutical industry boss. But Donald Rumsfeld's resume now has a new, rather surprising addition: video-game app developer.

Donald Rumsfeld Ray Lustig / TW:P Staff

The 83-year-old's late foray into the gaming world is called Churchill Solitaire and has chalked up an impressive 4.5/5 customer rating in the App Store.

Byers Market Newsletter Get breaking news and insider analysis on the rapidly changing world of media and technology right to your inbox. This site is protected by recaptcha

According to Rumsfeld, the app is a variation on solitaire that former British Prime Minister Sir Winston Churchill devised and played with a young protégé named André de Staercke during World War II.

Staercke later became a NATO diplomat and taught the game to Rumsfeld in the 1970s.

"Up until a few years ago, there were probably a dozen or so people in the entire world who knew how to play this game," Rumsfeld wrote in a Medium post late Sunday. "Winston Churchill was gone. André de Staercke, as well. And I knew I wouldn’t be around forever. There was every chance the game Churchill so enjoyed could be lost to the ages."

Unlike the regular version, Churchill Solitaire involves two decks (instead of one), 10 rows of cards (instead of seven), and an extra end-game goal called the "Devil's Six."

"Churchill Solitaire is not a game for everyone," Rumsfeld said. "It takes patience and perseverance, cunning and concentration, and strategy and sacrifice."

The game has a World War II theme, set against a backdrop of air-raid sirens and historical newspaper clippings. Rumsfeld worked with developers — he admits "I can't say I had much of an idea of what an app even was" — and gained the endorsement of the Churchill family.

The app is free to download but includes in-game purchases. Rumsfeld and the Churchill family's profits are going to charity.