Build it. Press play. Find out if it stands.
Play Drystack — free, in your browser
Drystack is a free daily structural engineering game. Every day there is one challenge, the same for every player — raise a tower to a target height in the wind, carry a load across a ravine, or hold a weight out over a drop — and you design a structure to meet it from timber beams, steel columns, steel braces, deck platforms and dry stone ballast. Then you press PLAY and surrender it to gravity. The structure takes its own weight, the test load is lowered onto the marker, sometimes the ground shakes, and it flexes, creaks, settles — and either holds or comes down. The physics are real and they are the same on every device: pieces are bolted wherever they meet at a point, bolts can shear or bend open into hinges, beams snap, braces kink when pushed, and stone rests on nothing but friction. If it fell, it will fall the same way again, so every collapse tells you exactly what to fix. Rebuild, test again, and once it stands, trim pieces and add margin to climb today’s leaderboard. A new challenge arrives at midnight UTC.
Each day brings one engineering challenge, identical for every player. It is one of three kinds — reach a height, span a gap with a load on it, or hold a load out over a drop — with a twist that changes with the day: a water tank on the roof, a stiff wind, a sea stack to build on, a tremor, a dropped load, no steel on site, or no footings at all. Monday is gentle; Sunday is the hard one.
You build on a one-metre grid. Wherever two pieces pass through the same point they are bolted together, and you can see every bolt. Pieces that only touch are not joined: a stone resting on a deck is held by friction and its own weight, nothing more. That difference — connected versus merely stacked — is the heart of the game.
When you press PLAY the build locks and the test runs: gravity comes on, the structure takes its own weight, the load is lowered onto the marker, the site’s wind blows from the left, and on some days the ground shakes. It passes if it still meets the challenge once everything has settled. If it fails, the result names the first thing that gave way — a bolt that sheared, a beam that snapped, a brace that buckled, or a whole frame that tipped or racked over.
Every piece has a job. Timber beams are light and cheap but weak in bending. Steel columns carry enormous loads down their length. Steel braces are strong when pulled and kink when pushed, and they pass behind other pieces so they can cross the frame. Decks are the stiffest thing in bending, so loads sit on them. Stone ballast is 700 kg of dry stone that is never bolted — it holds things down.
A structure that stands scores 1000, plus 40 for every piece under the day’s limit, plus 5 for every percent of capacity it still has in reserve, plus 25 per metre above the target on tower days. Collapses score nothing. Tests are unlimited and your best standing structure is what goes on the daily leaderboard.
Drystack is a free daily structural engineering game you play in your browser. Every day there is one challenge, the same for every player — reach a height, carry a load across a gap, or hold a load out over a drop. You design a structure from beams, columns, braces, decks and stone ballast, press PLAY, and watch real physics find out whether it stands. A day takes anywhere from five minutes to as long as you want to keep improving.
Yes, Drystack is completely free to play in your browser. No download, no signup, no paywall.
Read the day’s challenge, then build: pick a piece and drag from one grid point to another to place it. Pieces that meet at a point are bolted together; stone ballast just rests. When you think it will hold, press PLAY. Gravity comes on, the test load is lowered onto the marker and the structure either settles and holds or fails. If it fails you go straight back to your build with everything still in place, change what broke, and test again.
No. The simulation is fully deterministic: the same structure tested under the same challenge behaves the same way every time, on every device and in every browser. It avoids the parts of floating-point maths that differ between browsers, so a collapse you watch on your phone is the same collapse on a desktop. That is what makes the daily leaderboard fair, and it is what makes failure worth studying — if it fell, you can find out why.
The result tells you the first thing that gave way. A bolt can shear if it carries too much force, or bend open into a hinge if it is twisted too hard; a beam can snap in bending; a brace kinks if it is pushed instead of pulled; and a whole structure can tip over its base, slide, or rack sideways if nothing triangulates it. The structural view shows which pieces are pulled (blue) and pushed (orange), which joints are working hardest, and whether your centre of mass is over its base.
Timber beams are light and cheap but weak in bending. Steel columns are heavy and very strong along their length. Steel braces are strong in tension but buckle in compression, and they pass behind other pieces so they can cross a frame. Deck platforms are stiff in bending, so loads should sit on them. Stone ballast weighs 700 kg and is never bolted — it holds structures down, which is where the game gets its name: dry stacking is building with weight and friction alone, no mortar.
Only structures that stand score. Passing is worth 1000 points, each piece under the day’s limit adds 40, each percent of capacity the structure still has in reserve adds 5, and on tower days each metre above the target adds 25. The result screen shows every part separately. Tests are unlimited, and your best standing structure of the day is what counts on the leaderboard.
Yes — one a day, at midnight UTC, the same for everyone. The kind of challenge rotates between height, span and cantilever, and the difficulty follows the week: approachable on Monday and Tuesday, hardest on Sunday. Every day’s challenge is checked by building and testing a reference structure before it is ever shown, so it is always possible. Your streak counts days on which your structure stood.
Yes. It is built for touch: tap a piece, then drag between two points (or tap one point, then another) to place it, tap a piece to select, rotate or remove it, and pinch to zoom. The simulation is light enough to run smoothly on a phone.
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