Buy from me
To buy the game from me directly, first download the demo. Then, buy the game from this page. 
After you've bought the game, click "back to overture interactive" for your download link. Place the file you get in the same folder as the Kurovadis demo in order to unlock the full game.

If you have one of the original txt file unlocks, it won't work with the new version. Contact me through email with your purchase info (or tell me about the file you have), and I can send you the DLL version.

Buy on DLsite
Alternatively, the game can be purchased from Dlsite.