ArmADev is an eclipse plugin/feature for developing missions and add-ons for the games ARMA 2 and ARMA 2: Operation Arrowhead
You must have Eclipse Indigo (3.7) installed. You should also have ARMA 2 or ARMA 2:Operation Arrowhead, although it is not strictly required
To install this feature, do this:
Eclipse may ask you to install additional plug-ins to satisfy dependencies.
Any ARMAScript .sqf file should be opened in the ArmAScript editor now. There is also new project types available.
This needs expansion :)