Duke Nukem Pi!

wget http://apt.duke4.net/pool/main/d/duke3d-shareware/duke3d-shareware_1.3d-20_all.deb
wget http://www.berryterminal.com/dl/eduke32_2.0.0rpi+svn2789_armel.deb
sudo dpkg -i duke3d-shareware_1.3d-20_all.deb
sudo dpkg -i eduke32_2.0.0rpi+svn2789_armel.deb
If you want to use head phones instead of HDMI audio: amixer cset numid=3 1
eduke32 

Source: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=35&t=9934