Don't forget the NES and Atari 5200 versions (the latter being a homebrew single 64k cartridge)
There are plug-in's etc that let you play the original games via emulators across the Internet with other players.
Yeah but I think you have to arrange those games, or no? With Planet Mule's game (and its free) you can usually find a game during evenings and not too long of wait (maybe 10 minutes) during day.
Try it, I want the gamer base to grow so more people to play. The server usually has 2 server hosted games and anyone can host a game on his PC and the opening for that game is then shown on the server's lobby for others to see it so if the two server hosted games are full and enough people in lobby you can host a game and get one going quick.