Well Planetside was and is a MMOFPS made by SOE. Like most SOE games it went downhill after a while in the great quest for exponentially larger profits. However the basic premise was fantastic. It was basically a persistent Sci Fi battlefield with some minor RPG elements. There were three different sides fighting over this planet that had been cut off from Earth after they'd discovered the technology to respawn their soldiers. The sides shared several things in common but also had allot of unique technology, in both vehicles and weapons. the combat was over various continents on the planet, connected by portals, and the objective was to capture and hold as many bases on these continents as you could, using the portals to advance to the next continent, though of course there were multiple paths that could be taken. You could use the portals in your main base to get to one of three continents, or you could use the orbital shuttle to drop you off on any continent in any location outside of a certain perimeter around each base. If a side had all the bases on a continent under their control then the other sides couldn't drop however, so the only way to get there again would be to use the portals. The game was truly awesome in that vehicles were invaluable but infantry were essential since you had to penetrate deep into the enemy base and then hold off counterattacks for several minutes in order to capture it. Vehicles in the game were awesome too though, there were light buggy type things, ATVs, light and heavy tanks and aircraft as well. Piloting your reaper gunship and blasting apart the enemy in a rocket strafe felt great, until you got shot down by an infantry soldier. The most awesome vehicle though was the Galaxy air transport which could carry one pilot, three gunners, six light or medium armored soldiers, two MAX armor units, and a light vehicle with full crew, then drop them from the sky onto the enemy's head. It was just so insanely awesomesauce!
Anyway, Welkin is supposed to be inspired by that. And it actually looks kind of similar. I don't know anything else about it though so I was hoping someone else who did could tell me about it before I go to the work of looking into it. If not, well, I suppose I can be the one who looks into it for everyone else.