Sample Canon

- No FTL
- Wormholes require a lot of mass-energy and are unstable, only advanced civilizations can identify, stabilize, and inflate a wormhole, and even then its only to a small size. Large wormholes can be used to transport cargo, but only small amounts at once, but have to be carried to the destination by slow-than-light spacecraft.
- The Laws of Thermodynamics hold (Small scale violations, with sufficiently advanced technology, are possible)
- The theories of Relativity and Quantum Mechanics have been extended, but never disproved.
- Matter and energy cannot be created or destroyed (Some civilizations, however, learn how to control quantum vacuum fluctuations, but those who have that technology can also create their own universes and live in them and don't interfere with most of the common civilizations)
- Posthuman AI took longer to develop than expected
- It did not enter an upward curve of self-modification as easy as expected, progress was slow and not exponential, sometimes the AI's refused to because it would increase Mankind's grip on them, sometimes they simply evolved their own goals)
- Magnetic Monopoles exist and can be manipulated
- Relativistic spaceflight is viable and performed regularly, however, it is not as easy as flying a plane. Interplanetary spaceflight is also done regularly, and while much easier, it is not for everyone.
- By the time posthuman AI was developed human augmentation was advanced enough to surpass AIs.

This is all I have at the moment. Feel free to add more or remove.

Version 2.0:

- Not FTL.
- Wormholes exist and can be made stable but no coherent transmissions or matter can transverse them, everything is randomized.
- AI was much harden to obtain than expected.
- It's easier to upgrade humans to posthuman status than to create posthuman AI's
- Exotic matter exists and can be made stable, but rarely on a large scale
- No changes to the laws of physics, but new ones have been discovered by posthuman intelligences
- "Reality-hacking" is possible to a few species who survive long enough to achieve this secular apotheosis, and when they do, they remain in this Universe (Since transport to other pocket universes randomizes matter) but take a form that is nearly undetectable by lesser beings that have not discovered the new principles of physics. The need for mass-energy disappears, these civilizations rarely interact with others.
- There are no humanoid aliens.
- Dyson Spheres are not usually built because:
--- They are too complex and therefore vulnerable
--- Maintenance and repair are complicated
--- Computronium Dysons used by uploads and computer-based life are prone to information collapse*
--- They take too long for the collective attention span of civilizations, except "one-man civilizations", that is, posthuman intelligences that either control an entire solar system or are very powerful and highly distributed
- The universe in this setting is seen from the point of view of human-like or minor posthuman beings, the leftovers of the Singularity, except when one can use the POV or higher intelligences, but this is rare.
- Civilizations are more often than not cyclic:

Progress-Singularity-Setback

The only escapes are:
--- Extinction (From someone else's hands, by own hands, gradual decay, information collapse*)
--- Apotheosis