I would try to sove it this way: You can download the list and see who's where etc. But then you are not able to edit the list. You have to join a game that is listed. The gameserver machine will then send the info about you to the server that is hosting the list and list script. The game server will send the infos frequently, or at least whenever something has chanched. The gameserver also has to send a frequent livesign ping (say every 2 minutes). If that ping is missing, the game will be removed from the list.
This can be done, although you should be prepared for pauses due to single threading of blitz apps. So when a server responds slowly, the game will hang for some time, for all players, unless you try to work around this problem somehow (eg by using external threads).
But basicly, the most sensitive part will be: make this entire thing sabotage proof. Make sure it cannot be DOSed, crashed or fooled etc by some stupid people, cause it's likely somebody will try to do that.
You need to work with data autentification etc. (use hard to guess checksums, probably encryption)
This can be done, although you should be prepared for pauses due to single threading of blitz apps. So when a server responds slowly, the game will hang for some time, for all players, unless you try to work around this problem somehow (eg by using external threads).
But basicly, the most sensitive part will be: make this entire thing sabotage proof. Make sure it cannot be DOSed, crashed or fooled etc by some stupid people, cause it's likely somebody will try to do that.
You need to work with data autentification etc. (use hard to guess checksums, probably encryption)