They use Alien technology and the Eternumn skin lines are all alien-esque. they have a theme that looks similar.... But another thing I remember is that the headhunters were in the Omega Squad skin line trailer.
So are the yordles in some kind of top-secret war against aliens?
Not really. I'm don't pay special attention to alternate universes' lore, but the wiki has that information: Eternum, Headhunter and Omega Squad.
Eternum and Headhunter are mutally exclusive because you can't have both machines ruling the world and high-tech predators roaming free (unless I'm reading something wrong). The Omega Squad isn't very descriptive, but they are in the same universe as Headhunter.
My head canon when it comes down to alternate universes is: every universe is disconnected unless stated otherwise, for example Coven and Elderwood. ######They're all connected within League of Legends though. Kinda like how Dissidia Final Fantasy connects many FF characters.
