📦 Crate Stack

Why the tower narrows faster than it feels like it should

Crate Stack is a pure reflex game with a single control: drop. What makes it harder than it looks is not the timing but the bookkeeping underneath it. When a crate lands, the game keeps exactly the overlap between it and the crate below and throws the rest away. So a drop that lands 12 pixels off centre does not cost you 12 pixels on one side — it costs you 12 pixels of total width, permanently, and every crate stacked above inherits the narrower deck.

Perfects buy width back, but only a sliver. The perfect window is four pixels either side of dead centre — about one percent of the 360-pixel board. Land inside it and the crate snaps into alignment and comes back six pixels wider, re-centred on the stack, and it can never grow past the 240 pixels you started with. That gives you an exchange rate worth writing down:

Two clean perfects repay one twelve-pixel miss. Four unremarkable drops that each felt "close enough" can eat a fifth of your deck before the tower is ten high. The run does not end when you get sloppy; it ends four layers later, when the deck finally gets narrower than your reaction time.

The sweep speeds up on a schedule, not a clock

The active crate slides at two pixels per tick on the first layer and gains 0.14 pixels per tick for every layer you add, until it pins at six from layer 29 onward. That is 120 pixels a second at the bottom of the tower and 360 at the top. Crucially the ramp is tied to the layer count and not to elapsed time, so a cautious player and a fast one face the identical curve — nobody gets an easier climb for stalling.

Put that against the fixed four-pixel window and you can see the squeeze exactly. Early on, the crate spends about four frames — roughly 67 milliseconds — inside the perfect band. By the speed cap it crosses the same band in about 22 milliseconds, less than a frame and a half. The window never widens. Every perfect you fail to take early is one you will not get later.

Habits that add ten layers

1. Farm perfects in the first five layers. The sweep is at its slowest, the camera has not started scrolling yet, and six pixels banked at layer three is six pixels you still have at layer thirty.
2. Watch the dashed guide line, not the crate. The game draws a dotted line straight down from the centre of the moving crate. Line that up with the centre of the stack below and you are aiming at the actual thing the code measures, instead of eyeballing two edges at once.
3. Fix your lead, not your reflexes. Within a layer the crate moves at a constant known speed, so consistent lateness is a constant error. Tap a fixed distance early and adjust the distance, rather than trying to react faster each time.
4. Once the crate is narrower than about 50 pixels, stop chasing perfects. At the speed cap the crate covers roughly 54 pixels in a 150-millisecond reaction. When the deck is thinner than that, a drop aimed at dead centre and delivered a beat late has zero overlap — and zero overlap is not a trim, it is the end of the run. Aim for the middle of the stack and accept a few pixels off.
5. Remember that a bad layer is survivable and a miss is not. Any overlap at all, even a sliver, keeps the tower alive. There is no penalty for an ugly layer beyond the width it takes.

Nothing about the run is uploaded while you play. The Post button on the game-over card is the only thing that sends anything, and only when you type a name and press it: one record holding the game id, that name, the score and a server timestamp. The name is remembered in your browser under kp_player so you do not retype it. Skip the button and nothing leaves the page; if the leaderboard service is unreachable, the game plays exactly the same and only the online board goes quiet.