Thanks so much for the extensive feedback! Really appreciate you took some time to think of additional features too.
I'll definitely try to expand on the concept, and if I can use shapes that are larger than just 4 squares, then ideas like your splitter would be a really fun addition to spice up the variety. In the same breath you could also make half/half blocks that have two colors where they each attach to a different color.
Before I rattle on, yeah just thanks for leaving something extra!