You have multiplayer on the same computer, with the possibility to split the screen.
If you want network support, then you'll have to wait the 2006 version that should be available within 2 months (and it'll be free for all 2005 users). This network play should support connection over the Internet, but only with people having a very good ping (30ms, maybe 60ms).
Though, please note the network support is still not guaranteed right now, I will do it and test it on next month.
== Mana Games ==
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