There was the original premise, to be entirely set on Earth. People didn't like the humans, and the second series was something of a soft reboot, set on Cybertron.
Megatron: Origin was written for publication at Dreamwave and fits more into that continuity. It's pretty incompatible with the rest of the IDW universe. I don't even count it.
All Hail Megatron was a total reboot, then retconned (clumsily) into the previous continuity. Continuum actually re-wrote quite a few of the events of the pre-AHM stories.
Now, this series seems to be set a few years after AHM, with Earth totally rebuilt from the Decepticons practically destroying it, and the Autobots in hiding on Earth for reasons I'm not sure about since I'm waiting for paperbacks. So definitely two hard reboots, three if you count the retconning of AHM into the previous continuity.
Ok, then I am glad I used the term "several". They've been soft-rebooting since the beginning of the Spotlight series, and it's gotten super messy with everything floating around AHM, especially Spotlight Drift.
Darth Vader is becoming the Mickey Mouse of Star Wars.
Kylo Ren - came from Space Brooklyn, although he moved to Space Williamsburg before it was trendy.
The use of a lightsaber does not make one a Jedi, it is the ability to not use it.