Rift Runners = Players (In this case PCs)

Genera = Anything, we are just going to start in our reality to get an idea that we are going to be traveling a lot of places and to jump into a game. Adventure 1 in other words. I did it this way so that it is easier to think about your character as being many things in many places instead of just "I have a character here, now I have another character there."

Dimension = An adventure. The science is actually pretty irrelevant. So far as a dimensional intersection, (it would be a really strange space/time bubble if there was no height, seems a little cramped to me) take a look though, basically the dimensions in question are the same necessities to building an adventure, just fancied up. I will make an edit. I have actually done 2 others but for some reason is omitting changes that I have made.

If you are trying to think of ideas for a character, just get the core of the "who" and the "what you want them to be doing to help" down, and then tag it to a tangible someone you might actually slap with a fish today.