Hourglass

Rules

Hourglass is played on a pinched board: a full row of 4, a narrow row of 2 squeezed in the middle, then another full row of 4. and take turns filling in an open square. Get 3 in a row — a row, a column, or a diagonal — to win.

There's one catch, and it only applies to the very first move of the game: it can't land on one of the four squares directly above or below the narrow middle row (shown grayed out until that first move is made). Those four squares are each the meeting point of a row, a column, and a diagonal at once, which is too strong a head start for whoever goes first. Corners and the two middle squares are all fair game to open on. After that first move, every square is open to both players for the rest of the game.

Who moves first alternates each new game.

New to this one? Medium is a good place to start — it plays a tight, exact game except for the occasional careless opening move, so a win over a draw is well earned.

Controls

Squares are named by their row and position: T1–T4 across the top row, W2–W3 for the narrow waist in the middle (only 2 squares wide), and B1–B4 across the bottom row. Column numbers line up straight down the board, so W2 sits directly under T2, and B2 sits directly under W2.

With a mouse or touchscreen: tap an open square.

With a keyboard: type the row letter (t, w, or b) followed by the column number, like "t2" or "b4," into the box below the board, then press Enter or Place to confirm.

Type status (or just the start of it, like "sta") and press Enter or Place at any time -- even when it isn't your turn -- to have the board read back to you.

Roots

Hourglass plays like a compact Tic-Tac-Toe on an unusual pinched board, 3 in a row instead of 4 — and it's a closer relative than it looks at a glance. The board is only one cell bigger, 10 to Tic-Tac-Toe's 9, but the pinch adds two extra diagonals that a plain 3×3 grid doesn't have room for, so there are 10 ways to win here against Tic-Tac-Toe's 8. Three-in-a-row on a small board is genuinely ancient — Three Men's Morris, played for centuries before it grew into the better-known Nine Men's Morris, is the closest classic ancestor.

Under the hood

Hourglass only has three difficulty levels, not four, because the board is small enough that there's no natural place to insert a shallower search the way some of the other games here do. Easy is intentionally forgetful: it only checks for its own winning move half the time, and even when it looks for a block, it only catches it 35% of the time. Medium and Hard both run a full, exact search of whatever's left of the game on every single turn — the board only has 10 cells, so solving it out is instant even starting from a blank slate every single turn — nothing gets carried over from the move before, and it still doesn't matter. There's no shallower version of "perfect" to fall back to. The one difference between them lives entirely in their opening move: Medium has a 40% chance, and Hard a 10% chance, of playing something genuinely careless there instead — a random legal cell, no win or block awareness involved. Every move after that, for both of them, is exact. So a win against either one always traces back to that one early stumble being punished through real play, not a lapse somewhere in the middle of the game.

The board's real danger lives in four specific cells — the ones sitting directly above and below the narrow middle row. Each is the intersection of a horizontal line, a vertical line, and a diagonal line all at once, so a piece placed there can be doing triple duty toward a win. The game blocks both players from opening on one of these cells, which by itself is enough to force a draw with perfect play from either side. That block is also the one place this version departs from the original notebook game — everything else about Hourglass is exactly as it was played growing up; this restriction got added once it was clear an open first move let whoever went first grab too much of an edge. But that restriction only applies to the very first move of the game — every hot cell is fully back in play for the rest of it, and a real match uncovered a fork that lands on one of these cells well into the middle of the game, quietly completing two different two-in-a-rows at once (you can watch that exact game play out in the teaser animation on the homepage). The danger doesn't retire after move one; it just goes quiet for a while.

Unlike Corner 'Round, Hourglass is fully solved in this project: exhaustively checking every position confirmed that avoiding the hot cells on the opening move is, by itself, enough to guarantee a draw against perfect play, no matter who moves first. That's not just a skill-ceiling footnote — it's also proof that neither seat has a structural edge, which is why real games alternate who starts each time. That might sound like it should flatten the skill ceiling the way a fully-solved game usually does, but it hasn't in practice — the hot cells keep resurfacing as live threats deep into ordinary games, so a sharper player keeps getting rewarded for tracking them long after the opening restriction has stopped doing any work.