Litmus: Colour Sort Puzzle

Join a cheerful crew on a small research station and sort sealed element capsules into bays until each bay holds one element. Pip the lab robot stops any move that would put two reactive elements together, and tells you why.

180 LEVELS ON SIX DECKS
Docking Bay, Hab Deck, Lab Deck, Greenhouse, Workshop and Observatory, 30 levels each. Every deck brings a new family of elements and one new idea.

PIP SAYS NOT THAT BAY
Lithium, sodium and potassium cannot go on chlorine or bromine, and hydrogen cannot go on oxygen. Pip explains why in one line. Helium, neon and argon never react with anything in the game, so they can sit with any capsule.

FILL YOUR PERIODIC TABLE
Sort a full bay of an element for the first time and its cell lights up with a fact card. 22 elements to find.

ONE PUZZLE A DAY
A new daily puzzle, the same for everyone. Missed days stay on the calendar and you can catch up for free.

HELP WHEN YOU WANT IT
Hints are shown by Pip. After the free one, a hint is an optional short ad. If you're stuck, you can choose to watch an ad for an extra empty bay, or say no thanks.

NO LIVES, NO TIMERS
No energy either. Undo and restart are always free, and every capsule has a symbol, so you never rely on color alone.

Element facts are short, simplified lines for a puzzle game, based on the Royal Society of Chemistry periodic table.

Recent changes:
Fixes to level progression