By adding the PPA you get automatic updates with new versions for both the game engine and the editor.
To install any packages from the PPA open a console and enter this (you have to do this only once):
sudo add-apt-repository ppa:rpluess/dragondreams
sudo apt-get update
To install the Drag[en]gine Game Engine enter this:
sudo apt-get install dragengine
To install the Drag[en]gine IGDE enter this:
sudo apt-get install deigde
You get now the newest versions whenever your system updates itself.