It's a little odd to talk about one dude's work as a subgenre, but when you look at a comic like Gødland or that old 1963 miniseries, it starts to make sense. Kirby had a very distinctive thing going on, and there was more to it than just his art style. The most kirbyesque Kirby works were the ones where he went beyond superheroes and into what I'd describe as sci-fi mythology: the various Fourth World books, The Eternals, Kamandi: The Last Boy on Earth, OMAC, and others.
I'd love to run a game sometime that mines that vein for setting material, but doesn't actually reproduce any specific elements. Here's what I've got right now.
Kaliba is inhabited by a race of living gods. They're largely human in appearance, but an idealized kind of human, with a wide range of vivid coloration, sometimes including patterned skin, or even a metallic sheen. Their eyes glow brilliantly, as does their golden blood. They're very nearly immortal: ageless, immune to all disease, astonishingly resilient, and able to regenerate any damage short of the destruction of the brain or heart. What's more, they're invested with a brilliant cosmic energy that they wield to create a variety of effects. Their power is so flexible that they've never developed technology in the sense that we're familiar with. Their cities and clothing are built through the direct application of their strength and energies. They can also invest simple metal and stone tools with some of their power, or use it to change and sculpt living things for their own purposes. They've populated their world with extravagantly modified Earth animals, and are served by semi-sapient worker creatures.
Shath is also home to a race of gods, but one for more physiologically diverse than those of Kaliba. While still mostly humanoid, they exhibit monstrous or animalistic features as well. Their coloration is just as unusual as the gods of Kaliba, but less vivid, tending towards, dull, pale, or muddy tones. Their blood is black, with a faint iridescent sheen. They are essentially immortal, with less resilience and more regenerative capability than the Kalibas, but they have a tendency to change gradually over time, becoming ever more inhuman with the centuries. They wield a cosmic power of their own, but theirs is dark and murky, and far better at affecting its wielder than affecting the outside world. The Shathen tend to be gifted with powers of shape-shifting, invisibility, intangibility, and the like. Unlike the gods of Kaliba, they have needed technology. Their machines are in many ways more advanced than those of Earth, but are generally bulky, unsubtle, inefficient, and sometimes dangerous to be around.
For reasons that have long since passed beyond memory, the two races of gods have been at war with each other, on and off, for as long as they've been aware of each other. It's a bitter conflict, driven by the same hatred it generates, bereft of ideology or purpose.
The planets of the gods are hidden from Earth, but Earth isn't hidden from them. Both races visited our world often our distant past. The Kalibas were called gods, and devils, and fairies. The Shathen were also called these things, as well as dragons, vampires, goblins, and the like. Both races taught, terrorized, enslaved, and enthralled humanity, shaping our history and culture. But, most of all, they fought each other. Sometimes directly in divine battles that scarred the Earth's landscape for millenia, and sometimes by human proxies, through wars and pogroms and myths that we will never truly understand.
Now, though, the gods call Earth neutral ground, and their endless, senseless war is in one of its colder phases. Humanity has forgotten them, and both races of gods work to keep it that way, both for our good and their own. In the past, the gods' interactions with mortals had done us much harm. And now, as our technology has grown to rival that of Shath--and shows every sign of surpassing it, someday--it's very possible that humanity could actually threaten the gods to some degree.
Of course, by the same token, it's obvious that mankind could be the key to the Kalibas' or the Shathen's final victory, if only they could quietly turn enough of us to their cause. So the war between the gods has become a secret struggle to gain influence on Earth. But, as each side becomes aware of the other's breaches of the treaty, their cold war is heating up.
...Okay, so if that's enough setting info, I'll finally talk about just how this could be played. Naturally, I'd use Mutants & Masterminds or some variant of it. Player characters would probably be a mixed group of Kalibas and Shathen, also possibly Kalibas-Shathen hybrids, god-human hybrids, regular humans who've gotten ahold of powerful divine artifacts, or even regular humans who are just really awesome at stuff. Maybe servitor creatures from Kaliba or robots from Shath, too. Just how these people would know each other and why they'd work together--and, yeah, I'd really rather we have that worked out from the very beginning--would depend on just what kind of mix of characters we end up with. I like the idea of the group being centered around young gods from opposite sides of the line who became friends and hope to end the war, or gods and humans who are breaking the rules to learn about each other. And, naturally, some larger external problem would loom before long, forcing the PCs to stand alone between the warring gods against a threat only they are aware of.
The whole tone I'd be going for with this game is BIG. Epic, bombastic, mythic stuff. Interplanetary adventure, apocalyptic threats, the discovery of secrets older than mankind, divine tragedy, that kind of thing. Not superheroes. Sci-fi mythology.
Would it work? With the right players, hell yes. I can only hope to actually get a chance like that some day.