http://bugs.winehq.org/show_bug.cgi?id=7996
--- Comment #5 from Kenton Groombridge kenton.groombridge@us.army.mil 2007-09-03 08:06:30 --- I determined a bit more on what the problem is:
If the game is hosted either by dedicated server or staring a local server using Wine, then joining the game will fail. If I start a server on a real Windows system, then I can join it fine using Serious Sam under Wine.
So the issue is the game runs fine using Wine, but hosting a game using Wine doesn't work. The game has to be hosted on a real Windows system.