We have replaced our daily table soccer break with a round of teeworlds at work. It's a great game for that purpose. Like table soccer, the game mechanics are simple enough that anyone can join and have fun instantly, but there is a lot of opportunity to gain skills by learning to use the rope efficiently, combined with "classic" FPS stunts such as rocket jumps. Highly recommended.

I also recall playing Soldat a lot back in high school. I think there wasn't a Linux version available, which I guess is why I stopped. Perhaps one will appear now that it is open source?