Free Windows & Linux network games

[Harteex]

I'm looking for some fun network games... games that are playable on both windows and linux. I already know about FreeCraft and BZFlag, do you know any other fun games?

 

[Remote]

If I'm not mistaken and / or completely wrong www.flightgear.org is a free windows / linux flight simulator. Don't know if it has networking capabilities though...

 

[Harteex]

Thanks, I'll check it out.
However, I guess I'm more into action and RTS games.