From the game page just in case you missed it:
Controls and how to play
Remember Vacumator is searching for a path in clockwise order and goes to the first empty tile that is available.
Place your blocks is such order that when it goes to that path the block will direct it to its goal.
- Choose direction switch tool from toolbar and place it on grid
- While hovering on a tile with direction switch block press R to rotate it
- Hold RMB to move camera
- Mouse wheel to zoom
- Press play mode to activate vacumator