The brilliant Dark Souls series has surpassed 8.5m sales, and more than 3.25m of those were on PC.
The numbers come from a Japanese presentation by From Software, reported by Famitsu and relayed/made sense of on NeoGAF.
According to the numbers:
darksouls
Dark Souls has sold 2,828,000 units worldwide
Dark Souls: Prepare to Die Edition ("with Artorias of the Abyss") has sold 2,765,000 units worldwide
Dark Souls 2 has sold 2,311,000 units worldwide
Dark Souls 2: Scholar of the First Sin has sold 600,000 units worldwide
That's a total of 8,504,000 sold
The PC-specific number comes from SteamSpy, which may not be entirely accurate. According to SteamSpy:
Dark Souls: Prepare to Die Edition has sold 1,977,541 (+/- 33,243) units on Steam
Dark Souls 2 has sold 994,455 (+/- 23,621) units on Steam
Dark Souls 2: Scholars of the First Sin has sold 256,772 (+/- 12,021) units on Steam
That's a total of 3,228,768 sold (+/- 68,885)
However, SteamSpy's Dark Souls 2 PC figure is in dispute. Start with the Dark Souls 2 total of 2.3m. Subtract from that 1.2m - the figure Bandai Namco said it shipped within three weeks of Dark Souls 2 launch (before the PC version came out and could add to the total). Subtract another 350,000 for sales of Dark Souls 2 on PS3 in Japan, a version From Software published. That leaves around 700,000 attributable to PC. But that's nearly 300,000 fewer units than SteamSpy attributed to Dark Souls 2 on PC (994,455). Thank you commenters grassyknoll and CatButler for putting that in terms I could understand.
Dark Souls wasn't originally intended for PC, which seems ludicrous now. It was a fan petition - with more than 100,000 signatures - that encouraged publisher Bandai Namco to go ahead with it.
The PC version turned out to be a ropey port but was made good by patron saint of the Dark Souls community, Durante, and the DSFix mod.
Dark Souls 2 was released on PC as well as PS3 and Xbox 360 from the off - well, almost a month late, but more or less the same.