
The game has a multiplayer mode, but you might have difficulties with figuring out how it works, because back in 2005 it was designed to work with ASE (a master server-like service defunct since 2008) and LAN and that's something different from today's reality.
Medek from CRC community has released a multiplayer guide to help you with this! You'll need Hamachi for this:
If it didn't help, please, let us know in the comments!
Invictus Games has also commented on a prospect of a modern, Steam based multiplayer:
We are considering adding Steam based online multiplayer. It depends how succesful the game is going to be. If there's a bigger demand for it, we can add such a feature.
As evidenced, it may or may not arrive at some point in the future! It all depends on your reception!