Mirror Beam· Advanced

Goal

Place mirrors to guide the laser beam from the source to the target.

Rules

Tap an empty cell to cycle mirrors (/ → \ → empty).
Mirrors reflect the beam 90°. Walls block the beam.
You must place all given mirrors to clear the puzzle. Check the remaining count at the top.
On Hard difficulty, the beam must pass through all checkpoints.

Try tracing backward from the target to figure out mirror positions.
Fixed mirrors (gray) are hints. Analyze their direction first.
Use undo freely. Experiment with different placements while watching the beam.

Mirror reflection puzzles train mental rotation and sequential planning. Spatial skills are trainable (effect size g=0.47) and planning tasks activate the prefrontal-parietal network.

Uttal, D. H. et al. (2013). "The malleability of spatial skills." Psychological Bulletin, 139(2), 352-402.
Baker, S. C. et al. (1996). "Neural systems engaged by planning." Neuropsychologia, 34(6), 515-526.