I say non-sci-fi because i don't plan on this being what you'd expect in any amount of typical science fiction, no futuristic/impossible technology, no time travel, nothing like that (even though technically this HAS to be sci fi since it's well, built on fictitious science)
the rp will be based around a simple premise, there are several dimensions in the multiverse, these dimensions manifest themselves under the guise of parallel universes, separate planes of existence and dream worlds, to name a few.
These dimensions are governed by the constantly fluctuating flow of dimensional energies that separate, sever, fuse, destroy, and create universes, but never bind them. That is the one constant in the multiverse, while two universes may very well come crashing together at one point and fuse into a single universe, two separate universes can never be connected while retaining their independence, and thus cross-dimensional travel is impossible.
at least it was until now.
someone from another universe has discovered and learned how to harness the dimensional energies that govern existence itself, and through the manipulation of the energies, has punched a hole in the 'wall' that separates his dimension from ours.
the result is that the energies from each respective universe have stated flowing and mixing together like if you put a divider in a container and filled one side with juice and the other with water, then poked a small hole into the divider.
as a result, the 'infiltrator' has discovered that any object that crosses over from one dimension to the other becomes part of the very hole that they punched. in other words, they very existence in the universe is what is serving as the basis for the gateway that is allowing the energies to mix, and then discovered that sentient beings that had crossed into another dimension possessed the ability to manipulate the very dimensional energies that now flowed through them, the energies that were the basis for creation itself.
however, the longer they stayed in another dimension, the greater grew teh hole that they had origianlly poked, allowing for more energy to flow through the rift but at the same time thretening the collapse of teh two linked universes, and perhaps the multiverse.
'the infiltrator', rather than try and fix this, has decided to accelerate it by pulling other beings from his world into ours and fusing them with our characters, turning us all into 'rifts' like him.
his goal, to cause the collapse of both worlds (and eventually the multiverse in its entirety) so that he can control the dimensional energies in their entirety (that includes those that we control) and become the new god of the multiverse, shaping it to his desires.
our characters will, like him, now posses the ability to essentially become gods with enough time, but for now our powers will be limited to what we could consider 'magic' or 'psycho kinesis' and it will be up to each of us on what we do with them from now on.
we can all chose to fight him and try to mend the 'rifts' between the two worlds, or we can try to beat him at his own game and become gods ourselves, or, if we want, some of us can join him and praise him as the father of all gods (which wouldn't be entirely incorrect).
ok, well, maybe not 'simple' premise, but yeah, anyone interested?