How to play

stackdle.io is a falling-block puzzle about one thing: the perfect clear. You clear every block and leave the board completely empty.

The daily puzzle

There are three new perfect clear puzzles every day, and everyone gets the same ones. You play them in order. A new set unlocks at midnight in your own time zone, and the bar above the board shows which clear you're on.

• Each clear gives you 11 pieces in a fixed order, listed in the side panel.
• Use 10 of them to fill the bottom 4 rows exactly. Every line clears and the board ends up empty.
• Nothing can go above the dashed line. If it does, or you run out of pieces, that clear starts over. Clears you already finished are kept.
• Hold is on. Holding swaps the current piece for the next one, which is how you choose 10 of the 11.
• You get 3 hints per clear. A hint shows where the next piece goes. Undo is allowed, but every undo is counted.
• Giving up ends the day. You keep the clears you finished, and you'll see a solution for the one you stopped on.
• The built-in solver has checked every puzzle, so there is always a solution.

The day's ranking puts more clears first, then fewer hints, then fewer attempts. Press Copy result to share how you did without spoiling anything:

stackdle.io #12 · 3/3 perfect clears
PC 1 🟩 1 try
PC 2 🟥🟩 2 tries · 💡1
PC 3 🟩 1 try
⏱ 4:12 · 1 undo · 0 finesse faults

Each 🟥 is a failed attempt and 🟩 is a clear. ⬛ marks the clear you gave up on, and ⬜ one you didn't reach.

Streaks

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

Practice modes

Finesse drill

The finesse tab has two modes. In Targets, an outline appears on an empty board. Get your piece into it with as few key presses as you can, then hard drop. If you used more presses than needed, you'll see the shorter sequence.

In Free stack you build however you like, with hold on. If a placement took extra presses, it's taken back straight away, the spot stays outlined, and you see the quickest 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 next to you. It tells you whether a perfect clear is still possible with your pieces. Press H for the next placement, or tick Show under the board to see the whole solution as numbered steps. You can also choose which bag position (PC #1 to #7) each attempt starts from.

40-line sprint

Clear 40 lines as fast as you can. You're timed, and pieces per second and finesse faults are counted as you go.

Controls

These are the defaults. You can change any of them from the gear button next to the board.

On phones and tablets, buttons appear under the board. Pieces don't fall on their own; a piece only locks when you hard drop it.

Settings

The gear button next to the board opens your settings.

• DAS (delayed auto shift) is how long you hold left or right before the piece starts sliding. Lower feels snappier.
• ARR (auto repeat rate) is how fast it slides once it starts. At 0 it goes straight to the wall.
• Experienced players mostly use a DAS of 6 to 8 frames (100 to 133 ms), ARR 0 and instant soft drop.
• Minimal blocks swaps the rounded, shiny blocks for flat squares on a darker board, if you prefer a plainer look.

Tips

Finesse

• Holding a key to slide counts as one press, 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, which is exactly 10 pieces.
• Don't cover a gap. An empty cell under a block usually means that row can't clear.
• Think of 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're the easiest to fit into whatever is left.