What the game is
The Skyline Witness is a sightline mystery — the classic skyscrapers puzzle, also published as towers or city-block puzzles, rebuilt as a detective case. Something valuable crossed the rooftops of a city square at midnight, lifted from a terrace or balcony in plain sight of the houses around it. Half the square swears it was at its windows. But the borough's height records burned years ago, and all that survives is the old surveyors' margin notes: for each end of each street and lane, how many rooftops they could count from there. Nothing else — not one building's height, apart from a few figures in the insurance papers.
You rebuild the skyline by entering heights. Every street (a row) and every lane (a column) holds one building of each height, and a rooftop is in view from an edge only when it stands taller than every building before it — so the tallies force every height by pure logic. Then the same rule does the detective work: every witness has sworn to what their own window showed them, and the finished skyline says exactly what each window could reach. Innocent witnesses tell the truth. One claim, in one statement, describes a view that window could never have shown — and its author was on the roofs.
Case procedure
- Start with the extremes. A tally of 1 means the nearest building is the tallest of all; a tally equal to the block's width means every rooftop shows, so the heights climb 1, 2, 3… in order from that end. Enter those first.
- Cap the buildings nearest a tally. A tally of 3 needs three rooftops to show, so the tallest building cannot stand in the first two places, the second-tallest not in the first place, and so on. Pencil what each building can still be.
- Add the two tallies on one line. When a street's two tallies add up to one more than the block's width, the tallest building stands exactly as many places in from one end as that end's tally says — the heights climb towards it and fall away beyond.
- Work the singles. Every street and lane holds one of each height. A building with one height left takes it; a height with one building left on its line goes there.
- Try the arrangements. When a line is nearly settled, list the ways it could still be arranged under its tallies and what you have placed — usually only one or two survive, and they agree on a building. This is the quiet workhorse of the whole block.
- Look out from every window. With the skyline standing, take the sightline glass to each witness's home and read every claim against the roofs: what is in view, what is hidden, how many rooftops show each way. Tick the claims that hold, cross the one that cannot, and accuse.
The rulings that matter most
- In view means taller than everything before it. From any vantage — the edge of the block or a witness's window — a rooftop shows only when it stands taller than every building between it and the observer. A building between that is as tall or taller hides it.
- The observer's own building never blocks their view. Counting from a window, the building next door always counts as the first rooftop in view, whatever the observer's own height.
- One of each height per line — and the block turns two matching heights red the moment they share a street or lane, so a skyline can never quietly go wrong. The same red flags a finished line whose count is wrong and a line already showing more rooftops than its tally allows.
- Lost tallies are simply lost. A blank edge tells you nothing about that line — the block is still proved solvable from the tallies that survive.
- Brass heights are settled. Figures from the insurance papers cannot be changed and never lie.
- The glass reads your heights, not the answer. Rooftops it lights up are proved by your own entries; anything that depends on a building you have not yet placed stays grey.
- Every innocent's claims are all true. Only one claim in the whole file fails, and it belongs to the thief. Two claims by the same witness are never inconsistent with each other; only the real skyline exposes the lie.
- The statements cannot convict alone. Every case is proved to have a second skyline, consistent with the brass heights, on which every sworn claim holds — so the warrant always needs the tallies.
Choosing a rank
Street Level (a four-by-four block, four witnesses) teaches the tallies and the glass in about ten minutes: two claims per witness, and the lie is always about the scene of the theft itself. Rooftop Run (five-by-five, six witnesses) is the full method: sparser tallies, landmarks joining the map, and claims about counts, far ends of streets and blocked neighbours. Bird's Eye (six-by-six, eight witnesses, three claims apiece) is the long shift: the fewest tallies, verified heights as the currency that keeps the logic honest, and a file where only careful testing of every window finds the impossible claim. Bigger blocks add more interlocking deduction, never unfair steps.
Fairness, hints and reveal
Every case is generated and then proved before you see it. The generator's solver must complete the whole block using only the deductions described in this manual — the same reasoning you use at the desk — which guarantees exactly one skyline fits the tallies and that no guessing is ever required. When a block needs more help, the bureau prints another brass height before the case ships; when it needs too much, the block is thrown away and regrown. The detective layer passes its own proofs: every claim is tested through the same rule the glass applies, exactly one fails, each claim is false on some skyline consistent with the brass heights so nothing is a tautology, and a decoy skyline on which every claim holds proves the statements alone can never point at the thief. Check flags heights that cannot be right without adding any. Hints escalate politely: the first press names a deduction and the reasoning behind it; a second press points at the exact building, and the height is still yours to enter. Reveal unseals the surveyors' own ledger and excludes the case from your cases-cracked tally. Wrong accusations are stamped on the file; the case stays open — and naming the right witness with the wrong claim is its own stamped failure, because the magistrate signs only for the claim their window could not show them.
Printing a case
Any case can be downloaded as a PDF pack built entirely in your browser from the same case number as the on-screen block: the briefing, the laws and every witness statement with its rulings on the case sheet, one full block sheet with tallies, addresses, verified heights and named buildings sized for pencil work, and an optional answer key with the solved skyline, every claim tested and the warrant. Skyscrapers puzzles are print natives — a pack runs about three or four A4 sheets and suits classrooms, puzzle clubs and long train journeys, and the case number on the cover reopens the same block on screen.
Questions from the surveyors' desk
What is The Skyline Witness?
The Skyline Witness is a sightline mystery — the classic skyscrapers puzzle rebuilt as a detective case. Something valuable crossed the rooftops of a city square at midnight, and half the square swears it was at its windows. The borough’s height records burned years ago; all that survives is the surveyors’ margin notes, counting how many rooftops could be seen from each end of each street and lane. Rebuilding every building’s height by pure deduction gives you the skyline — and the skyline tells you exactly what each witness’s window could and could not show them. Exactly one sworn claim is impossible, and the witness who made it was on the roofs.
How do the tallies work?
Every square of the block is a building between one storey and the block’s width tall, and every street (a row) and every lane (a column) holds one building of each height, like a Latin square. The numbers on the edges are the surveyors’ tallies: how many rooftops were in view from that end of that street or lane. A rooftop is in view when it stands taller than every building before it — so a tally of 1 means the nearest building is the tallest of all, and a tally equal to the block’s width means the heights climb in order. Blank edges are notes that were lost.
What are the brass heights?
A few buildings come with their heights already printed in brass — figures recovered from the insurance papers. They cannot be changed and never lie. They are part of the case’s design: some blocks need a fixed point or two before pure logic can carry the rest, and the bureau supplies exactly as many as the logic needs and no more.
What is the sightline glass?
The sightline glass is the surveyor’s tool for testing a window. Choose it on the height pad, or press “Look out from” on any witness statement, and the block shows what that building’s windows can reach along its street and lane: rooftops in view light up green, hidden ones are hatched, and anything that depends on a height you have not entered yet stays grey. It reads only your own entries, never the hidden answer — so it can only ever show you what you have already proved.
How does the skyline catch the thief?
Every witness swears two or three claims about what they saw from their own window: that they watched the scene of the theft all evening, that a landmark was hidden behind a taller roof, that exactly three rooftops showed down the lane. Innocent witnesses tell the truth. The thief was never at their window at all, and one of their claims describes a view their window could not possibly have shown them. Test each claim against the finished skyline with the glass, and accuse the witness whose claim fails — naming the claim.
Can the statements alone give the thief away?
No, and that is proved for every case. Before a case ships, the generator finds a second skyline — one that agrees with every brass height — on which every sworn claim, the lie included, is true. So the statements are consistent with each other and with the printed heights; only the real skyline, which the tallies force, exposes the lie. Nothing is readable early: each claim is also checked to be false on at least one skyline consistent with the brass heights, so no claim is a tautology.
Is every block guaranteed solvable without guessing?
Yes. Every case is proved before you see it: the generator’s solver must complete the whole block using only named, human deductions — the tally extremes, the height caps a tally imposes, the two-tally rule, singles along a street or lane, and trying the arrangements a line can take. If a block would ever require a guess, the bureau prints another brass height before the case ships, or the block is thrown away and regrown.
What do Check, Hint and Reveal do?
Check flags any height that cannot be right, without adding any of its own. Hints come in two strengths: the first press names a deduction and explains the reasoning — which tally, which line, which rule; pressing again points at the exact building and its height, though the entry is still yours to make. Reveal unseals the surveyors’ own ledger and raises the whole skyline with every claim tested, and a revealed case never joins your cases-cracked tally.
What are the case ranks?
Street Level is a four-by-four block with four witnesses — a whole case in about ten minutes, where the lie is always about the scene itself. Rooftop Run works a five-by-five block against six witnesses, with claims about landmarks, counts and far ends of streets joining the file. Bird’s Eye is the six-by-six block with eight witnesses and three claims apiece: sparse tallies, verified heights as the currency that keeps the logic honest, and a file where only careful testing of every window finds the impossible claim.
How is the accusation made?
Each witness statement carries an Accuse button. The bureau memo then asks for one more thing: which of that witness’s claims their window could not have shown them. Naming the right witness with the wrong claim is a stamped failure of its own; the case stays open either way, and wrong arrests never end the night.
Can I play on a phone?
Yes. The block sizes itself to the screen, every building is a generous tap target, and the height pad sits directly beneath the board. Your heights, notes and claim ticks save automatically between visits, and each case has a case number so the same block can be reopened.
Can I print a case?
Yes. Any case can be downloaded as a PDF pack built entirely in your browser from the same case number as the on-screen block: the briefing, the laws, every witness statement with its rulings on the case sheet, one full block sheet with tallies, addresses, verified heights and named buildings sized for pencil work, and an optional answer key with the solved skyline, every claim tested and the warrant. Nothing is uploaded anywhere.
Is The Skyline Witness free?
Yes. All ranks are free to play in your browser with no account or sign-up. A new case is one click away, and every case is generated fresh — the block is built, proved fair, and dressed with new witnesses, landmarks and sworn claims, so no two skylines read the same.