Dwarf Fortress (opens in new tab) hit Steam yesterday, but you probably know that already. In fact, there's a decent chance you own it. Kitfox Games, who published DF's "premium" Steam version, enlisted the aid of an economist (opens in new tab) before yesterday's release to try to predict how many copies the game would end up selling after its ASCII version spent 16 years as a free download on Bay 12's website (opens in new tab). The prediction was respectable: About 160,000 copies sold in two months.
Dwarf Fortress hit that in under 24 hours (opens in new tab).
In fairness to Kitfox's poor economist, they did describe the experience of predicting DF's sales numbers as "like trying to drive with the rearview mirror," and their two-month estimates ranged from under 100,000 sold to over a million copies sold. That's less an indictment of their predictive powers than it is evidence of how difficult it is to accurately forecast sales and the behaviour of Steam's algorithms.
It's all the harder because, while Kitfox's back catalogue has its share of bangers, it's never published anything with the vast history and fanatical fanbase of Dwarf Fortress. It was always going to be an outlier.
In fact, as I write this, the most popular thread on the game's Steam discussion forum is one started by a perplexed user asking if fans have "been playing free DF for 25 years [sic] and just waiting for an opportunity to pay $30?". It's currently accrued a hundred pages of people saying "Yes" (opens in new tab). I'm no economist, but I think the higher end of those earlier estimates might end up being quite a lot closer to the mark about two months from now.
We rather liked gaming's premier dwarf-traumatiser at PCG, scoring the prettied-up Steam version 84% in our Dwarf Fortress review (opens in new tab) and calling it "an experience you won't match anywhere else". It's still a hyper-complex failure simulator "you have to meet more than halfway," but let's be honest, what other free game ever had legions of fans queuing up to drop $30 on it 16 years after release?