GGPO (Good Game Peace Out) is pretty much only for fighting games, but it works really well for them. People from all over the world come to play and there is some serious talent around.
Getting GGPO to run isn't really hard, but it's not dead simple either. I'll try to cover some of the more common problems people have with it.
(The official instructions can be found here.)
Step 1 and 2 are pretty straightforward. Download and install Adobe AIR and the GGPO client.
Step 3 is a little more difficult. If you are behind a router you need to forward the following ports to your computer:
UDP ports 6000-6009 (inbound/outbound)
TCP port 7000 (outbound)
Port forwarding sounds harder than it actually is.
Here is a pretty simple guide.
Basically you just need to get into your router and tell it not to block connections to your computer from the GGPO server.
Find the folder you installed GGPO to and create a new folder called ROMS. This is where you will put your MAME roms.
Launch GGPO.exe and you will come to a login screen. Click on where it says create account and follow the instructions to recieve your username and password. Enter your info on the login screen and click Login.
(Here is where things may get weird.)
If everything is working well at this point, great! If not, you may have to do one more thing.
You may click Login and have nothing happen at all. If that is the case, you need to download this .zip file,
and make a new folder on your desktop. Name it whatever you want, but DON'T name it GGPO. Extract the contents of the zipped file you just downloaded directly into your new folder. Create a new ROMS folder and place your roms in it. Run GGPO.exe to launch GGPO.
Now it should be (hopefully) working for you.
If you still have problems, visit the forums.
After you are in, you need to configure your controller. As far as I can tell you can only do this while you are in a match. I'd suggest playing a friend first, or challenging yourself and then taking a look at all the options available.
5 is insert coin and 1 and 2 are player 1 & 2 start respectively.
It sounds difficult to get GGPO running, but it's well worth it. Once you get to beating up a total stranger while others are watching a lot of that arcade excitement will come back!
GGPO has other neat features, like being able to watch others play so you can just chill and watch if you don't feel like playing.
Lots of people regularly set up tournaments for different games on various forums and spectators can watch and record the matches.
Here is a list of games that are currently supported:
Dungeons & Dragons: Shadow over Mystara
Fatal Fury Special
Garou: Mark of the Wolves
Hyper Street Fighter 2
JoJo's Bizarre Adventure
King of Fighters 2000
King of Fighters 2002
King of Fighters 97
King of Fighters 98 (by far the most popular game, it has three rooms.)
Last Blade 2
Marvel Super Heroes
Marvel Super Heroes vs.Street Fighter
Marvel vs. Capcom
Metal Slug X- Super Vehicle-001
Night Warriors: Darkstalkers' Revenge
Samurai Shodown 2
Samurai Shodown IV
Samurai Shodown 5 Special
Street Fighter Alpha
Street Fighter Alpha 2
Street Fighter Alpha 2 Gold
Street Fighter Alpha 3
Street Fighter II Koryu
Street Fighter II: Championship Edition
Street Fighter III: 3rd Strike
Super Gem Fighter: Mini Mix
Super Puzzle Fighter II Turbo
X-Men Children of the Atom
X-Men vs. Street Fighter
One last thing...GGPO seems to go down all the time, if it's not working for you then try again later or check the forums to see what the issue is.
I hope that was helpful for everyone, if you want to play sometime or need any help with it drop by the chat or our forums and we'll see what's up!
I made these vids of some people playing today while writing this post :)
Discuss this topic on the forums!