Hi all,
I've just finished a video on the gamerules for Oh no... INVASION!!! coming to Essen this autumn. You can check it out here.
http://www.youtube.com/watch?v=oSZ6YSUWNP4 (if the link doesn't work, search for Oh no... INVASION!!! how to play)
A short overview of the process.
Flash: Since I had all the images already, I could do all the scenes in Adobe Flash. A somewhat steep learning curve, but worth it if you can get your hands on a copy of Flash.
Garage band: Narration was done in Garage Band (free on Macs and a few dollars/euros on iOS). I was able to do the sound effects of the first scene, plus enhance my own voice to make it a bit more understandable.
iMovie: Also free on Macs (or small download). Took me around 2 days to put everything together and learn the basics, but it's very intuitive.
If you want me to elaborate on anything. Just ask. Otherwise, please enjoy