One interesting thing is that there are quite a few more states of matter than solid, liquid, gas and plasma (although not at normal conditions of temperature and pressure). You might consider the following states:
Supercritical fluid
Degenerate matter
Electron-degenerate matter
Neutron-degenerate matter
Strange matter
Quantum spin Hall state
Bose-Einstein condensate
Fermionic condensate
Superconductivity
Superfluid
Supersolid
Quantum spin liquid
String-net liquid
Time crystals
Rydberg polaron
Black superionic ice
Quark-gluon plasma
Theoretical state where the weak nuclear force, strong nuclear force, electromagnetic and gravitational force were combined due to the high energy density of the early universe (at the age of 10^-35 seconds after the Big Bang).
This is more physics than anything else. Playing with states of matter, fundamental forces and exotic objects in the universe (neutron stars, pulsars, black holes, etc.) is fun, but you would have very OP characters .I mean, if that's what you want, all well and good (plus it would be fun to try to find limitations or create a set of rules that would allow you to explain the powers system of the universe if you're into that sort of thing).
Also introducing literary interpretations of quantum mechanics gives you a million possibilities, although I think this would be going a bit off your proposal.
