Former US defense secretary Donald Rumsfeld is launching a mobile gaming app based on an obscure version of solitaire that Winston Churchill used to play. Churchill’s solitaire is more challenging and complex than other popular styles of the single-player card game, and Rumsfeld is advertising it as “the most diabolical version,” which would have been “lost to the ages” if not for his new app.

Rumsfeld, now 83, learned the game in 1973 from Belgian diplomat André de Staercke, who learned it from Churchill himself. In a post on Medium this morning, Rumsfeld writes that he spent the past two years developing the app—though of course he doesn’t pretend to know much about the technology involved:

To be more precise, I’ve been working with a team of developers to bring into the digital age a card game that dates back to at least the Second World War, and perhaps earlier. Starting this week, I’m pleased that it is now going to have a new life thanks to modern technology.

“I’ve signed off on something they call ‘UX’,” he jokes, proclaiming: “I am now officially in the app business.”

After obtaining permission from the Churchill family in 2014, Rumsfeld’s office worked with the Washington, DC-based Javelin agency (run by a former Rumsfeld aide) to create the app, which is called “Churchill Solitaire.” It’s on Apple’s current list of “best new games” and has a 4.5-star rating in the app store.

It’s a fitting foray into a new field for a statesman who will likely be remembered, like the former British prime minister Churchill, as one of the most controversial figures in modern history. Rumsfeld was the US’s most influential and heavily-criticized military strategist during his two tenures as defense secretary. He infamously authorized the use of torture for interrogations of prisoners during George W. Bush’s presidency.

The new game, Rumsfeld told the Wall Street Journal, ”requires you to be strategic, to look around corners, to think ahead, and to never give in—which is the phrase Churchill would have used.” Presumably, the game is meant to be addictive, but not painful.