DUNA: Sand Sort Color Puzzle

No ads, no lives, no in-app purchases, fully offline: DUNA is a free sand sort puzzle game, in the family of color sort and water sort puzzle games — with one twist no other sorting puzzle has: you can turn the whole world upside down. 500 levels, a daily puzzle, and a verified best solution for almost every level. Hourglasses, sand in layers, and one simple rule: sand only pours onto sand of the same colour, or into an empty hourglass. A level is done when every hourglass is emptied or filled with a single colour. TURN THE WORLD OVER One button tips the whole board 180°. In every hourglass the stack inverts: the colour buried at the bottom rises to the top. Turns are counted, and on some levels there is no solution without them. The generator carries a solver that checks every board before it reaches you: no level arrives without someone knowing it can be finished. A TRAIL THAT GIVES YOU ROOM Five hundred stops, and the difficulty climbs from first to last instead of levelling off after twenty minutes. The very first level already gives you eight hourglasses, four of them empty: room to manoeuvre, to get it wrong, to come back. Undo as often as you like, or restart a level from scratch — nothing is ever lost. CHIPPED HOURGLASSES Further along the trail, some hourglasses hold a stone. It never pours and never moves. Sand rests on top of it, but an hourglass capped by a stone is blocked — and since turning the world inverts the stones too, it opens as many hourglasses as it closes. You end up counting in parity. THE DETOURS One stop in twenty-five opens an optional branch: three stops set aside, where the world does not turn. In exchange, the sand gets one more empty hourglass. With no turn, a buried colour stays buried — you have to plan for it instead of rescuing it. Taking them or leaving them changes nothing about the crossing. TODAY'S STOP Each day, one more stop at the camp: the same one for everyone, for twenty-four hours. It does not advance your crossing — it is a visit. Its leaderboard empties every night. Nothing will remind you to go, and missing a day costs nothing: the counter adds up the days you crossed, it does not count days in a row. A TARGET THAT DOES NOT CHEAT Almost every level shows the move count of its BEST solution. Not an estimate: the exact value, computed offline, level by level. A handful of boards resist the computation and are then played with no target at all — we would rather show none than invent a number. Stay within it and your water skin stays full; past it, a drop evaporates now and then. Undo and restart give the water back — only the path you keep counts. WHAT YOU WILL NOT FIND No ads. No lives to wait for. No purchases. No account to create. The game is fully playable offline, from the first level to the last. An online leaderboard exists, and it is optional: nothing leaves your device until you ask for it in so many words. If you join, what travels is the name you choose, a randomly drawn identifier that derives from no property of your phone, the country you choose if any, and for each game its level and its moves — which the server replays to verify — plus the week number for the weekly Great Crossing. Nothing else. One button in the settings erases it all. MADE BY HAND No visual is an image: everything is drawn at runtime, from the sand to the dunes behind it. The sounds are synthesised in the game, not recorded — the music too. Nothing is taken from another game. ACCESSIBLE Distinct patterns for each sand, for anyone who tells colours apart poorly. And every hourglass is spoken aloud for screen readers — its contents, but also its state: blocked, chipped, empty. Three hints per level if you get stuck, and the game tells you when a board can no longer be solved. The trail keeps the stops you have cleared, and you can replay any of them: you will find exactly the same sand waiting.