Touhou: Scarlet Curiosity is one of those fan made games. Originally released for Windows in Japan in 2014, it soon qualified for a Sony platform called Play, Doujin!, where it was re-released on PlayStation 4 in February 2016. And just a few months later, it was brought to English speaking audiences with the help of XSEED Games. And a couple of years after that, XSEED Games has now brought it back to PC, with the latest release on Steam.
Source: N4G PC Touhou: Scarlet Curiosity review – ChristCenteredGamer