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Spectral Horn

Puzzle, Educational · Filip Paulů

Not rated yet

Single player

Split a beam of white light with a glass unicorn horn and steer each colour into its matching sensor.

Ways to play

Each option is checked separately: an app for one system says nothing about browsers or other systems.

  • Desktop browser

    Play on the developer's website

    Opens the developer's website. (play.js13kgames.com)

    Installation
    Not needed
    Registration
    No registration
    Price
    Free
    Controls
    Mouse
    Compatibility
    Started and played in headless Chrome on macOS at 1280 x 720 with the mouse: the first level was completed and the second begun.
    Checked 16 Oct 2026 · HeapPlay game scout
    Version
    Not specified

About this game

Spectral Horn is an optics puzzle. A beam of white light crosses the screen, and a unicorn with a crystal horn stands nearby. Move the unicorn into the beam and the horn splits the light into a rainbow; your task is to bring the colour each sensor asks for onto that sensor and hold it there until it charges and locks.

You drag the unicorn's body to move it, drag the ring around the horn to turn it, and use two small buttons for half-degree turns. The light follows real refraction: violet bends more than red, so moving or turning the horn shifts the whole band of colours. Later levels add mirrors, several sensors at once and colours that must be mixed back together. The build played here has 17 levels.

It was made by Filip Paulů for js13kGames 2026, a competition for browser games of at most 13 kilobytes, and won first place overall. The entry page also links to a longer "director's cut" on the author's own site, which was not checked for this listing.

Screenshots and video

Spectral Horn: green light steered onto the sensor in the first level

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