In the early 1990s, Doom was famously installed on more PCs than Windows itself—but how many was that, actually?

We all know Doom was so popular, so monumental, that it changed videogames forever. As a society, we're still obsessed with installing Doom on increasingly improbable devices, from pregnancy tests to vapes. But sometimes I run into an old factoid about Doom, some detail from its heyday that I'd forgotten, that still puts it in perspective.

Like this one: back in 1995, Doom was installed on more PCs than Windows.

I was reminded of this bit of trivia by re-reading an old PC Gamer magazine interview with John Carmack, published in November 2008, where the id Software programmer was reflecting on the benefits of open source and shareware. "We look back at the early days when the original Doom was shareware, and Microsoft did a study at the time that said there were more copies of Doom installed on computers than there were Windows 3.1. It's hard to characterise what exact value that is, to have people aware of your game but not paying you, but I certainly ...