Four in a Row

Seven columns, six rows, and a disc that falls to the lowest empty slot. It is a solved game — the first player wins from the middle column with perfect play — so nothing here pretends to play it perfectly: the strongest opponent searches ten plies and cannot reliably beat a copy of itself from the seat that ought to win, and more often than not loses or draws in it.

How it feels

• Immediate
• Sharper than it looks
• Two minutes to teach

What the design is for

• 01

  The column is the control

  You choose a column and gravity chooses the slot, so the board offers seven targets rather than forty-two. On a phone each one is a strip you can hit without looking.

• 02

  Four in any direction

  Rows, columns and both diagonals, against either wall and along the roof. The diagonal is the direction nobody checks, and the tutorial spends a whole step on it.

• 03

  A solved game, said out loud

  The first player wins this with perfect play. The opponents here do not play perfectly, and which of them beats which was measured over ninety-eight games a pairing — every two-ply opening, from both seats — rather than asserted.

• 04

  An opponent that does not depend on your computer

  Bounded by positions counted rather than by a clock, so the same seed plays the same column on a fast machine and a slow one — and a saved game replays exactly.

• 05

  Taught by playing

  Six steps: a drop, a row to finish, a threat you are not allowed to ignore first, the diagonal, the drawn frame most people have never seen — and then the frame to yourself.