LAN should work with a system like Hamachi or Comodo VPN

Also, Game Ranger had some sessions for Arcanum when I was playing my box version of Heroes III about a month ago...

Game Ranger would be my recommendation too.

Tried the multiplayer way back when, with as many people as the game would allow. It was very fun, even if it was real-time all the time. Since trading character to character was all but impossible (or so I remember it), and since NPCs had a tendency to steal anything lying on the ground, we used the trash cans to trade items. Ah, good times.

lol, awesome.
I'm liking that game pushes you into making shady drug deal-esque swaps to trade... how very underground :)
I often wondered could you pickpocket someone in multiplayer... could be rather tactical to steal all of some ones bullets and then challenge them to a dual :P
or while they're engaged in fighting off monsters, you could relieve them of all that heavy gold :D