Four-in-a-Row

Rules

Four-in-a-Row is played on a 7-wide, 6-tall grid. Two players — and — take turns dropping a marker into any of the 7 columns. A dropped piece falls straight down to the lowest open spot in that column.

Get 4 in a row — across, up-and-down, or diagonally — to win. If all 42 spots fill with no winner, it's a draw.

New to this one? Medium is a good place to start — it always takes a win when one's there, but only blocks yours about 85% of the time and doesn't look far past that, so it's forgiving without handing you the game outright.

Controls

Columns are lettered a through g, left to right -- same as real Connect Four notation. A dropped piece always falls to the lowest open row in that column, so there's no row to pick.

With a mouse or touchscreen: click any column, or the ↓ button above it, to drop a piece there.

With a keyboard: type a column letter into the box below the board -- "c," for example -- then press Enter or Drop.

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

Roots

Four-in-a-Row is the straight version of the drop-and-settle mechanic that Corner 'Round reinvents on a ring board. The core idea — pick a column, gravity decides the row — traces back to the broader n-in-a-row family that also includes Gomoku, and to much older align-four folk games played on paper long before any of them were sold in a box.

Under the hood

Easy has two independent coin flips before it ever falls back to a plain move: 50% odds it notices its own immediate win, then (only if that first check didn't fire) 30% odds it notices it needs to block yours. Miss both and it drops into whichever of the three columns nearest the center is legal, chosen at random -- centered but otherwise blind.

Medium and Hard both always take an immediate win the instant one exists, no dice roll involved. From there they diverge: Medium blocks your immediate win only 85% of the time (the rules panel's own number), Hard blocks it every time, no exceptions. Past that first look-ahead, both run a real alpha-beta minimax search -- Medium 2 plies deep, Hard 6 -- scoring a position by adding up every open line's own weight for however many of your pieces already sit in it (weights climb steeply: 1/12/60/100000 for one/two/three/four-in-a-row-in-progress, per line) and subtracting the same for the opponent's. A won line ends the search outright at a huge score, tie-broken to prefer whichever branch wins fastest or loses slowest. Both levels also try center columns first before the edges, the same move-ordering trick as Corner 'Round -- checking the moves most likely to be good first lets alpha-beta prune far more of the search tree, which is what makes Hard's 6-ply search fast enough to run in the browser at all.