Cairn: Stone Stacking Puzzle

Cairn is a stacking game about stones that disagree with each other. Each turn you are shown three stones and you place one. Every stone carries exactly one rule. There are eight: Slippery — things placed on it slide off Sticky — welds to whatever it touches Heavy — sinks into softer stone beneath it Twin — a copy joins your next hand Greedy — eats the stone directly below it, and grows Springy — bounces whatever lands on it Wide — broad and steady, but gains you almost no height Fragile — cracks, then shatters, if the cairn sways too hard Written out, that is a list. The game is what happens when two of them meet. Sticky on top of Slippery cancels the slide: the weld holds what the friction would not. Heavy on Fragile is a disaster you can watch arriving. Twin and Sticky together is an engine — the copy comes back in your next hand, welds to the one before it, and the column climbs straight. Greedy is the one that will catch you out. Put it under a Twin and it eats your own copy. None of that is scripted. It is one physics simulation and eight rules resolving inside it, which means the combinations nobody planned work the same way as the ones that were. The tower genuinely wobbles. A weld genuinely bends under load. When a Fragile stone is close to going, you can see the cracks in it. Score is height, in metres, measured at the highest point your cairn reached. A ruler runs up the side of the screen, one mark per metre, with a line left behind at your best. The run ends when the cairn does: a stone slides off the edge, a stone gets flung loose, or the whole thing comes down at once. Runs are about a minute long. The interesting decision is almost never "which stone is best" — it is which of the three in front of you is least likely to ruin what you have already built. One finger. Drag up off a card and let go over the cairn to place a stone; move before you let go to aim. Portrait, one hand, no other controls. The art is flat colour and plain shapes. That is a decision, not an unfinished state. The tower is the readout — you need to see at a glance which stone is which, where the weld is, and how far the whole thing is leaning — and decoration on top of that would be working against the game. Free, supported by ads shown between runs. No account. No sign-in. No in-app purchases.