The core was confused, how had it popped into existence as a fully formed multiverse core?
It knew there would be nothing until it created something. What about rules for subsidiary cores? No, a common system of physics seemed more important.
It decided to make things like gravity dependent on planetary cores and speed of light based on the skill of the universe cores. As such vehicles with a higher speed attribute could achieve faster than light travel and jump skills would be opposed by gravity attributes.
It set tasks to require so many success from a dice poll of twelve sided dice, starting with success on a 12 or Red, with progress through the colours of the terrestrial rainbow through 6 to 12 at violet. Skills would start at Red 1, letting them roll one twelve sided dice, with the number of dice upgraded for one Skill Point or the colour for five (six points could buy either R7 or O2)
It decided it was time to create its first universe core, by its own rules it would need to succeed on a check but it had given itself every ability and skill at V100.
57 successes, a higher number than it needed, it could give the core extra starting skill points.
The new core gave itself Blue summoning 10 which it decided was the relevant skill for creating Solar Cores. It would practice by creating several core-less galaxies using the training rules it's creator had set. It took several millenia but it improved to B30 which it felt was enough to now take the risk. 14 Successes and a solar core was made. It would continue practicing until it was ready for a proper galactic core.
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The new solar core practiced for centuries making lesser solar bodies, asteroids and uninhabited worlds without cores, until it had G70 summoning and was ready to make a planetary core for a sapient planet. The rest of the system would remain subject to its will. 20 Successes, this would start the planet off at O10 on summoning.
The planet in turn summoned a series of layers around its cores, preparing to create dungeons and towns with their own cores which in turn would summon monsters and adventurers. Dungeon cores had fewer needs so those got started first, when it reached O25. Only 2 successes meaning that the new core blamed its summoner and decided to try a demonic route.
Whilst the first dungeon core was practising its summoning, the planetary core continued to create more things, trying again at O26, up to five successes which still wasn't ideal giving the power but at least this dungeon was only planning on creating slimes.
The planet continued to build, making sure that the two dungeons were where their respective cores wanted tobe, trying to reconcile with them. It actually decided to tell the first core that the demons were its servants in the same way that they were intended to be servants of the planet core.
The two dungeons continued to practice summoning with lesser objects than the creatures, neither was ready for creatures yet.
Once the planet reached O50 it tried creating a blank town core near the demon dungeon, if it managed enough successes it was going to give it to the demon dungeon as a peace offering. 14 successes meant they were siblings rather than the same person as intended though the town core did defer to the dungeon core.