Stack Tower — the block timing game where overhang gets cut

One block slides left and right; tap and it stops where it is. Only the part overlapping the block below survives, and whatever sticks out falls away, so every miss makes the next block narrower. Each floor is a little faster. Land within 6 pixels of the block below and it counts as perfect, keeping the full width. Five perfects in a row and the trimmed width starts coming back. Your best floor count is saved only in this browser, with no install and no account.

How to use

  1. Tap the board or press Space (or Enter) to drop the moving block where it is.
  2. Only the overlap with the block below stays. Stick out to the right and the right piece falls; to the left and the left piece falls.
  3. Land within 6 pixels of the block below for a perfect: no trimming, and the combo goes up by one. A miss resets the combo to 0.
  4. No overlap at all and the block falls off — that game is over. Tap the result screen or hit Play again to start over instantly.

Block speed starts at 160 pixels per second, gains 4 per floor and stops at 360 — about 0.9 seconds for a 200-wide block to cross the board.

Even floors start from the left, odd floors from the right, so you can't play by rhythm alone.

Once the combo reaches 5, every perfect grows the width by 10 pixels, split evenly on both sides, never beyond the starting 200.

Your best is stored in this browser (localStorage) only and never sent to a server.

In depth

Rules — only the overlap stays

A 200-wide base sits on the board and a block of the same width slides back and forth above it. Tap and it stops; only the span overlapping the block below becomes the next floor. Overhang by 20 pixels on the right and that 20-pixel piece falls off, leaving 180.

This genre is usually called a timing stacker. There is one control, and every mistake carries into the next drop, so one miss makes the following one harder. This page is an independent implementation of those rules.

The real tension is your current width. A wide block forgives a miss; a 40-wide block crosses in a blink. Players who keep the width early are the ones who go far.

The perfect window — why 6 pixels

If the left edges differ by 6 pixels or less, the drop is perfect: no trimming, the block snaps onto the one below, the width holds and the combo rises by one.

A zero-pixel window would produce a looks-right-but-got-trimmed drop every time. At 160 pixels per second the block moves close to 3 pixels per frame (about 16 ms), so landing exactly on 0 is practically impossible. Six pixels is about two frames.

A perfect shows «Perfect!» and plays a note one step higher each time, so you can hear your combo without looking.

Width recovery — from combo 5

Once the combo hits 5, each perfect grows the width by 10 pixels, 5 on each side, never off the board, and never past the starting 200.

Without this rule width only shrinks, and at some point the only question left is when it ends. An exit — five in a row and you're back — gives a reason to focus after a bad drop.

Five is the threshold that stays closed to two lucky taps and opens only once you've found the rhythm. One miss resets the combo to 0 and you start the count again.

Speed curve — 4 pixels per floor

It starts at 160 pixels per second and adds 4 per floor: 200 at floor 10, 280 at 30, and the 360 cap at floor 50, constant from there.

The cap exists because of reaction time. At 360 pixels per second a 200-wide block crosses the 320-wide board in 0.89 seconds; any faster and the block has already passed by the time eyes and hand have responded. Skill stops showing above that.

The starting side alternates: even floors from the left edge, odd floors from the right. If it always came from one side you'd learn to tap on a beat without looking, which isn't this game.

How to stack well — protect the width early

The opening matters most. Chain perfects while it's slow and get the combo to 5 or more; later trims can then be recovered. Games that lose width in the first ten floors rarely reach 20.

Watch the left edge. The judgement compares left edges, and with equal widths, if the left matches the right does too. Trying to see the whole block makes your eyes wander.

When the block is narrow, aim for the turnaround. At the ends the block appears to slow as it reverses; its speed is the same, but the direction change makes it predictable. That only works if the tower sits near an edge, so parking the tower on one side is a tactic.

Taps are ignored for 0.4 seconds after the result appears, so a finger that tapped once more as the block fell doesn't start a new game by accident.

About this implementation

The block's position is a function of the time since the floor began. An add-per-frame approach would teleport the block when a sleeping tab wakes, and the drawn and judged positions could drift apart. A time function gives both from the same formula.

There is no randomness. Starting side, speed and width all follow from the floor number and previous drops, so the same tap at the same instant always gives the same result. The only luck involved is in your finger.

The board is drawn in 320×480 logical units and the pixel count follows display width and device scaling. Falling scraps are decoration outside the pure rules.

Your best stays in this browser. Nothing is sent to a server, so there is no global leaderboard, and clearing site data clears the record.

FAQ

What are the rules?

Tap to stop the sliding block, keep only the part overlapping the block below. That overlap becomes the next block's width, and no overlap ends the game. Floors are your score.

How is a perfect judged?

If the left edge of the dropped block is within 6 pixels of the left edge of the block below, it's perfect. Nothing is trimmed, the block snaps into place and the combo goes up. Six pixels is the margin that stops a visually correct but slightly late tap from counting as a miss.

Does trimmed width come back?

Yes — with a combo of 5 or more, every perfect returns 10 pixels. Five in a row from a tight spot brings you back, so a narrow block isn't the end. It never grows past the starting 200 though.

Why does it keep speeding up?

Every floor adds 4 pixels per second, up to a cap of 360. Above that, see-then-tap no longer fits inside human reaction time and the game turns into luck. From floor 50 on, speed is constant and only width matters.

Does it work on a phone?

Yes. Tap the board — one thumb is enough. It runs in the browser with no install or sign-up, and works offline.

Method and sources

What this tool bases its numbers on, and how far those numbers go.

What this tool is
A browser implementation of the timing-stacker genre. Not an official version of any app; the tolerance, speed and recovery rules are values chosen by this page.
Formula
Board width 320, starting width 200. Remaining width = length of the overlap with the block below. Left-edge difference ≤ 6 px is perfect (width kept, combo +1). Speed = min(360, 160 + floor × 4) px/s. With combo ≥ 5, each perfect adds 10 to the width (max 200).
Worked example
Drop a 200-wide block 12 px to the right and 188 remains while a 12 px scrap falls. Speed at floor 30 is 160 + 30 × 4 = 280 px/s.
Limitations
  • Touch latency varies by device. The same tap reaches the screen at different delays, so the 6 px window can feel tighter on older phones.
  • Your best is saved in this browser only. Clearing site data or opening on another device starts from 0.
  • A background tab pauses frames. On return the block is wherever the elapsed time puts it — it does not wait.
  • Pixel judgements use logical units (320 wide). On a large screen that is a longer physical distance.
Effective date
Last reviewed

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