How to play

Stackdle is a falling-block puzzle game built around one challenge: the perfect clear. You clear every block on the board, leaving it completely empty.

The daily puzzle

Every day there is one new puzzle, and everyone in the world gets the same one. A new puzzle unlocks at midnight in your own time zone.

• You get a fixed set of 11 pieces, shown in order in the side panel.
• Use 10 of them to fill the bottom 4 rows exactly, so every line clears and the board ends up empty.
• Nothing may go above the dashed line. If it does, or you run out of pieces, the attempt ends and you start again.
• Hold is allowed. Holding a piece lets you swap it for the next one, which is how you choose 10 of your 11 pieces.
• There are no hints. Undo is allowed, but every undo is counted.
• Every daily puzzle has been checked by the built-in solver, so a solution always exists.

Your result records how many attempts you needed, your time, undos and finesse faults. Press Copy result to share it without spoiling the answer:

Each 🟥 is a failed attempt, 🟩 is the solve, and ⬛ means you gave up. If you give up, Stackdle shows you a full solution so you can learn from it.

Streaks

Solve the daily puzzle on consecutive days to build a streak. Missing a day or giving up resets it to zero. Your streak, best streak, games played and solve rate are saved in your browser, so they stay on the device you play on.

Practice modes

Finesse drill

The finesse tab has two modes. In Targets, a target appears on an empty board. Move your piece into it using as few key presses as possible, then hard drop. Stackdle works out the shortest possible route and tells you if you used more presses than needed, showing the faster sequence.

In Free stack, you build up the board however you like, with hold turned on. If a placement took more presses than it needed, it is taken back straight away, the spot you chose stays outlined, and you are shown the fastest route so you can try again. Spots that need a soft drop or a spin aren't checked.

Perfect clear trainer

Unlimited perfect clear practice with a solver beside you. It tells you whether a perfect clear is still possible with your pieces. Press H for the next placement, or turn on Show under the board to see the whole solution with numbered steps. You can also pick which bag position (PC #1 to #7) each attempt starts from.

40-line sprint

Clear 40 lines as fast as you can. Stackdle times you and counts pieces per second and finesse faults as you go.

Controls

These are the defaults. You can change any of them in the Handling panel below the game.

On phones and tablets, on-screen buttons appear under the board. There is no gravity: a piece only locks when you hard drop it.

Handling settings

• DAS (delayed auto shift) is how long you hold left or right before the piece starts sliding. Lower feels faster.
• ARR (auto repeat rate) is how fast it slides once it starts. At 0 it moves straight to the wall.
• Most experienced players use a DAS of about 6–8 frames (100–133 ms), ARR 0 and instant soft drop.

Tips

Finesse

• Holding a key to slide counts as one press, the same as a tap.
• Going to a wall? Hold instead of tapping. One column off the wall? Hold, then tap back once.
• Rotate the short way: one counter-clockwise turn instead of three clockwise, and the 180 key instead of two turns.
• On a flat board, no placement ever needs more than 3 presses.

Perfect clears

• Four full rows is 40 cells, exactly 10 pieces.
• Never cover a gap. An empty cell under a block usually means that row can never clear.
• Picture the empty space as separate pockets. Each pocket has to hold a multiple of 4 cells.
• Save I and O pieces for the end. They are the easiest to fit into what is left.