SkyStack

Drop sliding blocks onto a growing tower and lose whatever hangs over the edge

Single player
arcade
tower
casual

▶ Play SkyStack Loads here in the page. No download, no account.

Prefer it full screen? Open SkyStack on its own.

About SkyStack

A tower builder in three dimensions, played with one input. Each new block slides back and forth above the tower, and when you drop it only the part overlapping the block below survives — the overhang is sliced off and tumbles away. Miss almost entirely and the block goes with it, ending the run. There is one life and no way to repair a bad cut except by earning it back.

The slide alternates axis every floor, left-to-right then front-to-back, so errors in the two directions accumulate independently. A tower can finish wide and paper-thin, or the other way round, depending on which direction you have been sloppier in. The block also speeds up as you climb, from a lazy sweep at ground level to roughly double that by the thirtieth floor, where it settles.

Your score is simply the number of floors. The camera drifts slowly around the tower as it grows, which is pleasant to watch and quietly makes the upper floors harder to judge.

What is different about this version

The tolerance is generous and the timing is not, which is an unusual pairing. Anything within about six per cent of the block's width snaps to a perfect fit rather than being cut, so you are not aiming at a pixel — but the block moves on a sine sweep, meaning it is travelling at its fastest exactly as it crosses the position you want. At ground level that gives you around seventy milliseconds inside the snap window; by the thirtieth floor, where the sweep speed caps out, it is nearer thirty-five. The other unusual rule is the recovery: three consecutive perfects grow the block back on both axes at once. Most stacking games only ever take width away, which makes a bad patch terminal. Here a bad patch is expensive but survivable if you can string three clean drops together.

How to play SkyStack

A block slides above the tower along one horizontal axis. Drop it when it lines up with the block below.
Anything hanging over the edge is cut off and falls; the block keeps only the overlap.
Land it close enough to dead centre and it snaps into a perfect fit with nothing lost.
Every third perfect in a row grows the block back a little, up to its original size.
Miss the tower and the run ends. There is no second chance.

Controls

Desktop	Click anywhere, or press Space, Enter or the down arrow, to drop. Escape or P pauses.
Phone or tablet	Tap anywhere on the screen to drop the block.
Players	One player. Any other characters on screen are run by the game.

Strategy

Perfects are not a bonus, they are the economy. A cut is permanent and compounds — every later block is measured against the shrunken one you just made — so a run that plays safe and accepts small cuts ends around floor fifteen with a sliver of a tower. The only source of width in the game is three perfects in a row, and it gives back size on both axes at once, which makes a streak worth chasing even at the cost of a risky drop.

Because the block sweeps on a sine curve it crawls at the ends of its travel and is quickest through the middle, which is unfortunately where you need it. The practical answer is to stop watching the block and watch the gap between its leading edge and the tower edge, releasing fractionally before the two line up. Consistency beats precision: whatever your personal lead time is, using the same one every drop keeps your error on one side, and error on one side is what the snap window forgives.

The alternating axis deserves separate thought. Left-right and front-back errors do not cancel, so if the tower is getting thin one way, that is the axis to slow down on even if it costs the streak. Full width and half depth is recoverable. Thin in both is not.

Mistakes that cost you the game

Accepting small cuts because they feel safe. Every cut makes the next target smaller, and the tower narrows faster than the tolerance does.
Dropping on the visual centre. The block is moving fastest there, so a shot aimed at the exact middle lands late almost every time.
Chasing a streak on the axis you are already thin in. Losing depth you cannot afford is worse than resetting the combo.

Tips

Release a fraction early. Your reaction time is part of the aim, and a consistent lead is easier for the snap to forgive than a variable one.
Watch the tower edge rather than the block; a closing gap is easier to time than an arriving object.
Count your perfects — the third in a row is the one that pays.
When an axis gets narrow, take the safe drop on that axis and rebuild on the other.
Give yourself a floor or two to readjust after the camera has turned.