Zenbound 2 is a great little game I got as part of the latest Humble Bundle, it's surprisingly fun and a very innovative style of game play, unlike anything else I have played in fact. Anyway i figured it would be a good game to have on my media center so here are the instructions for installing it on XBMCbuntu.
First you need to download the .deb file for Zenbound 2, once you have the .deb file you need to copy it to the home folder of your XBMCLive installation. For instructions on this follow my guide "Copy files to XBMC with Filezilla"
Then open a terminal or SSH into your XBMCbuntu box and run the following commands:
sudo dpkg -i zenbound2_20120325-1_i386.deb
mkdir scripts
cd scripts
nano zenbound2.sh
Now copy in the following text(it's ctrl + shift + v to paste at the terminal)
#!/bin/bash
openbox &
/usr/games/zenbound2
killall -9 openbox
and save the file(ctrl + x and then y to confirm)
chmod +x zenbound2.sh
Now you need to use "Advanced Launcher" addon to create a shortcut to start Zenbound 2 from within XBMC. Simply create a new launcher and point it as the zenbound2.sh file you created above(should be /home/xbmc/scripts/zenbound2.sh)
and that's it, have fun!