Schematic

It looks simple: a couple of clicks on switchers seem to be enough to make the energy flow in the right direction. But the schemes are designed so tricky that not every one can go through at once.

Optional challenges are for original brains and intuition.
Needed to see what the others can't see.
Find where the others fail.
Every level is a new intrigue, but you'll make it if you are ready to try.