東方非想天則 (pronounced Touhou Hisoutensoku, meaning "Eastern Unthinkable Natural Law") chronologically takes place after Undefined Fantastic Object (TH12) and also serves as expansion to Scarlet Weather Rhapsody. Henceforth it is referred to as TH12.3 instead of TH12.5.
Like its predecessors, Immaterial and Missing Power and Scarlet Weather Rhapsody, Touhou Hisoutensoku is a collaboration between ZUN and Tasogare Frontier. Tasogare Frontier is well-known for these fighting games, especially Eternal Fighter Zero.
Info from Touhou Wiki: http://touhou.wikia.com/wiki/Touhou_Hisoutensoku
This is the full game + the first patch (Version 1.01) and not a demo!
This game came out just today at the Comiket 76 (C76), so of course there is no english patch yet.
Since the whole game is 1 GB large yet the .rar'd version is only 1/4 of that, you get this in WinRAR format.