Age of Ethanols has a peer 2 peer over IP as configuration. Technically if your friend (or you) hosts a game, you fill out the hamachi IP address of the host and you should be able to join the game. Do not forget to open up the required port on your router, otherwise you might be unable to join.
Perhaps Stuffman or someone who has played 東方Ethanols actively can confirm this. I only played the older versions.
