When I started a DCU RP several months ago I had several people try to play Kryptonians even though it didn't really make sense in universe. I tried to come up with a way for all of us to be Kryptonians, but because I didn't want to play on Krypton where we'd have no powers I couldn't figure out how. I had an idea of how to do it today, though, when watching someone talk about how stupid the new movie Krytonians are, so I'll post it to see if anyone else wants to RP in that world.
The Kryptononians first discovered faster than light travel twelve thousand years ago. Curious about the universe they began visiting other systems, including Earth. On Earth some of the xenologists told the natives of Earth of their god Rao and the humans incorporated this into their religion as the sun god Ra. At this point Kryptonians reproduced almost entirely naturally and had not yet engaged in the extensive genetic engineering that they would later use, so while they possessed superhuman abilities due to the yellow sun they were fairly weak.
Though they traveled to 11 other galaxies, cataloguing everything they found, their colonization was limited to rare worlds which were similar to their homeworld, terraforming them to match Krypton as closely as possible. Eventually the scientific community realized that it would take thousands of years to analyze all of the information that they had gathered and built a great library on Krypton to store it all.
Their civilization thrived for thousands of years until a radical, monotheistic faction of Raoists came to power. They demanded that all convert to their sect of the religion and, after conquering the homeworld, began to conquer the colonies, killing any who refused to convert and forcing any who did convert to move back to Krypton so that they could live under Rao's light and return to him upon death.
One of these colony worlds was Veron, which orbited an orange star which granted the inhabitants improved health and abilities. Though it was one of the last worlds to be terraformed, its people devoted themselves to science, a large percent of their population studying the records of the 12 galaxies to discover any scientific secrets it held. When the radical sect came to attack them, they used that knowledge of science to destroy the invaders. The sect sent many more ships but eventually the attacks stopped, as they no longer wished risk death outside of Rao's light, where they would be forced to forever wonder the darkness, never returning to him.
The people of Veron then dedicated themselves to becoming as self sufficient as possible. They greatly expanded their mining operations and, through trade with other spacefaring races, they expanded their robotics and manufacturing to become completely self sufficient.
In the Krypton system the radical sect transformed into a much less violent form. The new form preached that genetic engineering would lead to them becoming true servants of Rao, as they could be born with genetics designed for the purpose Rao had chosen for them. They set up a caste system and giving natural birth became unheard of outside of rare accidents. And while the people were engineered for a specific purpose, there were certain genetic traits which everyone received, increasing their strength, cellular activity, etc.
The people of Veron engineered these same improvements into themselves, though not nearly as extensively, without the religious devotion that the Kryptonians did. The Veronians also continued to reproduce almost entirely naturally, while the extensive genetic alteration of the Kryptonians lowered their fertility rate more with every new iteration.
About 20 years ago several major events happened on Krypton which became major new on Veron, despite the fact that the Kryptonian government refused any official contact with Veron. The first event was the birth of a natural-born Kryptonian, an event which hadn't occured in hundreds of years if not more. The geneticists of Veron believed that one or both of the parents must be a mutant with an atavistic trait which gave them the ability to naturally reproduce.
The second event was Veronian scientists discovering that the planet Krypton was dangerously seismically unstable. A large fleet of transport ships was sent to the system to warn them and transport anyone who wished to leave to Veron. General Zod refused them entry to the system, however, threatening to destroy them if they tried to enter or spread this propaganda. He did inform the Council of this, but they agreed with him that it was Veronian propaganda, nothing more.
The third event was the destruction of Krypton. With its death, and the hibernation of all of the people at the in-system colonies, Veron could do nothing more for them. They considered waking up any cryogenically stored Kryptonians that they could find, but decided against it, as that could lead to another religious war. The few survivors would need to live among other beings for a time so that they could learn to accept other races and religions.
The Veronians began searching the galaxies for a world which they could send any survivors they found to, and in their search they came across radio transmissions from the planet Earth which mentioned a Kryptonian named "Superman". Wanting to learn more about this, the Stellar Relief Organization, the group which was searching the Rao system for survivors and trying to find a home for them, brought together a team to travel to Earth and meet this Kryptonian to see if perhaps Earth could become a home for the few hundred survivors they had found so far.
The RP would start with us arriving on Earth and landing outside Metropolis. While Veronian powers are similar to Kryptonian powers, we are not as strong physically (the strongest of us can lift just over a megatonne when fully charged on Earth). Our cells aren't optimized for solar collection to the same degree, as we didn't need it due to our sun putting out much more yellow light that Rao, so we don't absorb yellow sunlight near as quickly as Superman.
We do, however, get powers outside the standard set. Some of us have psychic abilities, some can tap into other forms of energy than heat, cold, and X-rays. We can fly, however, and have durability comparable to our strength.