I consider Creator 3 in 1 sets to be the closest theme to what Rebrickable is all about. Here's some parts, what can you build. Of course, these sets have hundreds of hours put into them to curate the parts to fit all models but essentially they are fun, versatile, and full of parts to add to your own MOC's. I wonder if this is a play 3-in-1 or a parts-pack 3-in-1, I call riding in the cow!
Alternate Builds and B-models, Sub-Sets and LEGO Idea reBuilds, together with MOVs and Modifications and Free, Premium and Freemium MOCs, these are LEGO creations that, besides Rebrickable, no other website in the world can offer you. If you have no idea what I am talking about, then allow me to review set 31086 Futuristic Flyer and show you all it creative possibilities.