The common story in all Transformers works is that the Cybertronians go to Earth. Has there ever been a story where the first encounter goes the other way? Humans arrive on Cybertron only to discover a planet wide civil war being waged.
Maybe a little-known comic book one-shot or something, but definitely not an actual franchise. That would be a really cool idea, though - a story taking place a few hundred years in our future, and sometime in our interstellar travels, we stumble upon the Autobot/Decepticon War.
I think the main problem with the story happening that way is that if humans were capable of space travel and landed on a planet filled with giant metal beings way more advanced than us blowing the crap out of each other on a planetary scale, the obvious reaction would be to GET THE FUCK OUT OF THERE. You'd have to invent some crazy reason for humans to want to stick around on Cybertron instead of going to the opposite end of the galaxy and never looking back. The existing series solve this problem by making the TFs come to us. When they come to Earth, we're stuck with them no matter what. Humans don't want a bunch of aliens fighting on our planet, but we don't exactly have the power to make them leave. And even if the story was set in the future when humanity has space travel, we wouldn't want to abandon our own planet just because some aliens set up camp there.
It's always been a bit fun to have humans on Cybertron. I think taking humans trapped far out of their comfort home environment always makes for good drama, especially when there's danger. As long as the Transformers aren't just portrayed as giant metal monsters and the humans get all the good story. As for humans being advanced enough to have the tech to get to Cybertron and why they'd not then just get the hell off the planet when they found they were in danger, maybe they end up there via some kind of human-built experimental Space Bridge. There's one on Earth and one on the Moon. The human team was suppposed to get sent from Earth to the Moon to trial the new system before going on via space shuttle to build the next Human Space Bridge on Mars and then on and further out into space to keep building new Bridges along the way, but there's an explosion and a malfunction and somehow they get hi-jacked by the distant Cybertronian Space Bridge system instead and sent there. There are no stored co-ordinates in the Cybertron Bridge for the humans to get home and they can't actually risk it because they don't know what caused the malfunction or even if their Earth and Moon Bridges still function or even exist anymore. That and the Space Bridge is, of course, Decepticon controlled and the humans have to flee to escape getting killed when discovered. The humans hook up with the Autobots, who promise that once peace is restored on Cybertron they'll help them find a way home, be it via a new Space Bridge system or building a spaceship once they've determined the proper co-ordinates to Earth. But for now the humans are stuck on Cybertron, in the middle of the TF war. Maybe that new spaceship promised for the end is actually the Ark and the accident that brought the humans to Cybertron also sent them four million years into the past - link to original G1 volcano crash on Earth! The human space Bridge could've even been derived from Earth-found Cybertronian tech from that ancient Ark crash and that's why the Cybertronian Bridge was able to hi-jack it during the explosion and malfunction. Mmm... circular continuity... And it also means you could have Optimus and Megatron and whatever. This could actually be a kind of prequel to the original G1 series. Of course the human team die in the crash. Maybe they sacrifice their lives making sure the Ark crashes in hope that the Decepticons won't end up on Earth (as opposed to Optimus making that choice to crash the Ark to try and take the Decepticons down with him). And in that long four million years in stasis, the TF lose all previous memory of humans and Earth. Okay, it's Stargate with Transformers, but fuck it.
