This game made my imagination run! Reminded me of the puzzles found on the Mario & Luigi Superstar Saga GBA Games.
Having each part only perform a single type of interaction, for levers or switches, Have to admit that found cheese (where the lower part alone could press switches, though level said that it was full robot) But, boy was that cheese good! Having the lower part have it's own responsibility felt way better. Add some in-between levels or ways to reunite the to parts on the next level, and you have a full fledge game premise. Really surprised you were able to implement the various mechanics across the levels.