For some great fun give RB3d multi play a try and tell your friends about it.

mplayer config settings
[KnownServers]
Server=UDP:217.72.51.103:47800; CSq_Swordfish
Server=UDP:rb3d.d3rwolf.de:47801 ; D3rWolf's Spielwiese
Server=UDP:rb3d.d3rwolf.de:47802 ; D3rWolf's Training Day
Server=UDP:162.156.245.184:47800 ;General de Deville's Alpine Hell
Server=UDP:162.156.245.184:47801 ; General de Deville's Hell

[MetaServers]
Server=TCP:rlgb.xs4all.nl:6001 ; Rens
Server=TCP:217.72.51.103:6001 ; Swordfish
Server=TCP:216.18.240.2:6001 ; Redux