this is the sample mod that comes with the SDK. I've compiled, and uploaded it on some free upload site, and you can get it here: http://uploading.com/files/29E0RV9L/Harbringer%20Mod.zip.html

The only thing the mod does is add the Harbringer from Uprising. It's a late game air unit that can switch between a machine gun and a like laser artillery thing. Very similair to the spectre airship from zero hour. The unit doesn't work exactly like it does in Uprising (It just hovers in the air rather than flying little circles) , but hey, alteast you can build it.

There you have it, one of the first mods for RA3!