Hisoutensoku is an expansion to Touhou 10.5 SWR and is a multiplayer fighting game made by Tasofro with ZUN's approval. It's easy to learn, hard to master battle system makes for fun and fast paced matches with counterhits often launching girls across the screen. Very fast when played right. As a P2P game, game hosts must forward ports in order to play it or use specific workarounds.
Extract into the folder of your choice. After launching th123e.exe, wait one or two seconds and then launch SokuRollLoader.exe to enable netplay. To host, hosting player forwards a port (detailed instructions are available on the internet) and provides IP with a port in an IP:Port format, launches the game with sokuroll and uses the Vs Network menu to start the server. Client connects to provided IP and port and plays game.