War es wirklich?

First person shooters:

• Tremulous
• Sauerbraten
• Nexuiz
• Warsow

Rogue-like games:

• Angband

Misc. games:

• Pingus (Lemmings-inspired)
• Frets on fire (Guitar-Hero-inspired)
• Solar Wolf
• SuperTux
• SuperTuxCart
• Tux Racer
• Vega Strike (Elite-inspired)

• apt-get install extremetuxracer
• apt-get install fretsonfire
• apt-get install lincity-ng
• apt-get install nexuiz
• apt-get install pingus
• apt-get install sauerbraten
• apt-get install solarwolf
• apt-get install supertux
• apt-get install supertuxkart
• apt-get install tremulous
• apt-get install tuxracer
• apt-get install vegastrike
• apt-get install warsow

Game packages

• apt-get install kdegames
• apt-get install ggz-gtk-games ggz-kde-games ggz-sdl-games

See also the list of open source games at Wikipedia