3 days 9 hours
FINAL FANTASY XV WINDOWS EDITION PLAYABLE DEMO
Dark Souls III
5 days 19 hours
FINAL FANTASY VIII
4 days 3 hours
DARK SOULS™: Prepare To Die™ Edition
2 days 15 hours
People said the same about Dark Souls.
I suspect Final Fantasy XV will sell a fair number of copies on PC. Let's not forget that even the FFXIII games sold hundreds of thousands of copies on Steam. And those weren't extensive ports of new games like this. Besides, FFXIV is kind of popular on PC and Steam as well.