Phantasmagoria of Flower View/Gameplay/Netplay
PoFV is also capable of multiplayer over the net, but is still in beta stages, and framerates/synchronization are very unstable, varying greatly from computer to computer.
First, download the patch from here. When you have it fully downloaded, open the th09_ver150a.exe and patch as you would with any other Touhou game. (Click Close, Yes, then select your PoFV folder to install it, then click OK.)
Note: After patching, you may encounter crashes upon startup--If this happens, you should keep your game folder somewhere in your C:\Program Files\* directory. If you need to keep it outside of Program Files, rename your game folder exactly to "Phantasmagoria of Flower View" without quotes. If you have to move it back into Program Files, you may need to rename it to something else.
Playing with your friends
Now that you've patched, there should be a text file called "IP.txt" inside of your PoFV folder, open it, and you'll see a part that says "IPAddress=192.168.0.1" or something similar. Replace the IP that's already there with the one of the friend whom you're going to play with. Make sure they do the same thing (except with your IP instead of theirs). From here, you can also change the sync rate, it's default on high, but if you want to change it, put a ; in front of whichever sync rate doesn't have one, and delete the ; in front of the sync rate that you want. Lower sync rates will produce better frame rates.
Once you're done setting up IP and sync stuff, start up PoFV, and go into match mode, pick the bottom option. It'll flash between two messages until both you and your friend are on that screen, and connected to each other. If it's stuck here, you messed up somewhere along the way. (It looks like it freezes, don't worry about this.) Once you're connected, you'll experience whatever lag you're going to receive immediately, and be pushed to difficulty menu, then character select. It should be noted that both versions of the game should have the same characters unlocked, neither having more than the other, as the characters on either side are not automatically unlocked just because one side has them.
Using the patch alone for netplay is known to be very laggy. However lag is greatly reduced (if not eliminated) through the use of a third-party application called Adonis. After patching to version 1.50a, download Adonis here and follow the instructions inside.
If you experience crashes as soon as you connect to a friend or the PoFV window does not appear despite connecting, try setting PoFV and adonise to Compatibility Mode. In one case, it was used on a 64-bit Windows 7 computer set to Windows Vista SP2 Compability Mode to get the game running.