One thing I've been circling with one of the as-yet-unfinished ideas is something that amounts to an entirely synthetic, personal, idiosyncratic set of fantastic tropes. Most people know about fantasy monsters of one kind or another, but I wanted to say "OK, let's take them all and throw them out, start from absolutely nothing. What do we come up with?" Sort of like that exercise I mentioned once where you list all the things you like, are curious about, etc. and then try to write a story that by design includes none of them.
I'm fascinated with the idea of taking a field of some kind (like "fantasy"), wiping everything from it that we could fall "fantasy", then seeing if we could have something grow there that would still have the same label. The same with "cyberpunk", or what have you. Call it an exercise in finding out what there truly is under the label, what the real essence of any type of story is.