PRISM: Light Puzzle

No ads. No in-app purchases. No account. Buy once and all 240 puzzles are yours. Works on a plane, works underground, works forever.

Tap, and the light bends.

PRISM is a puzzle with exactly one rule. Tap a piece and it turns 90 degrees; the light instantly finds a new path. Light every crystal with precisely the color it asks for, all at once, and the board is solved.

The controls need no explanation — one tap is all there is. If you want to know how light actually works, that is in here too.

■ Six chapters, 240 puzzles

I. Reflect — mirrors turn light by 90 degrees II. Split — a half-silvered mirror passes light and reflects it at once III. Disperse — a prism breaks white light into red, green and blue IV. Mix — two beams meeting at one crystal become a new color V. Refine — filters keep only what you want. Overshoot and you fail VI. Converge — everything you have learned, on one board

■ Every puzzle has exactly one answer

All 240 levels were machine-proven to have precisely one solution before shipping. No configuration works by accident, and no piece is decoration — rotate any of them and the solution breaks. The par shown on each level is not an estimate either; it is the true minimum, found by exhaustive search.

■ Nothing gets in your way

· No ads · No in-app purchases · No account, no sign-in · No networking — the app never asks for internet access · No data collected · No lives, no energy, no timers · No locked levels — stuck? just move on to the next one

You buy it once. That is the whole transaction.

■ This is real optics

The angle of reflection, dispersion through a prism, additive color mixing, selective absorption in a filter — every rule in this game comes from real physics. Entering a new chapter shows you the principle behind it on a single card. Tap once to dismiss it, or read them all later under "How light works".

It also states plainly where the game simplifies the physics.

■ If color is hard for you to tell apart

Every crystal carries its required color as a shape as well. Red is a triangle, green is a square, blue is a circle. A yellow crystal shows a triangle and a square side by side. You can finish every puzzle in this game without seeing color at all.

■ About the sound

The pitch of each rotation depends on where the piece sits on the grid — higher toward the top, lower toward the bottom. Solving a puzzle turns your hand into a short melody. It only uses a pentatonic scale, so no order of taps can sound wrong.

Turn the sound off and haptics take over the same job.

■ It is light

Nothing you see or hear was authored as a file. Apart from the app icon there are no images and no audio inside; every beam of light and every note is computed as you play. All 240 puzzles compress to 9 KB of data.