人機四子棋

Four in a Row vs AI: rules, tactics and practical play

Drop discs from above and connect four horizontally, vertically or diagonally. This guide reflects the controls and win conditions in the current browser build. It is reviewed by the PocketJoy game-testing team and maintained by Long-Term New Media Limited.

Rules and winning conditions

The board is an upright grid and you play the cyan discs, moving first. Tap the arrow above a column and your disc drops to the lowest empty cell in it — you choose the column, gravity chooses the row, and that is what separates Four in a Row from other line-up games as well as being the source of all its strategy. Four in a row horizontally, vertically or on either diagonal wins. If the grid fills with no line, the game is a draw. Three computer difficulty levels are available, with the hardest actively calculating multi-move threats. The status line always states whose turn it is, showing a thinking notice while the computer works so you never assume the game has frozen. Each column has its own drop arrow, which prevents mis-taps on neighbouring columns. The result dialog distinguishes wins, losses and draws, each with a short comment, and the record panel tracks wins and total games separately.

Match strategy

The first player has a natural advantage in the centre column, and opening in the exact middle is almost always the strongest move, because far more winning lines run through the centre than through any edge — on the standard seven-by-six board the central column participates in more than three times as many four-in-a-row combinations as the outermost one. Games are usually decided by the double threat: build a position where you can complete four in two different places at once, so your opponent can only block one. Two consequences of the gravity rule are worth internalising. First, if a winning cell can only be reached after your opponent plays the square beneath it, that threat is not live yet and should not be counted. Second, avoid moves that stack a square and hand your opponent the winning cell above it — a great many losses come from building the opposing win up to a playable height yourself. Stronger players also watch parity: on the standard board, threats on odd rows counting from the bottom favour the first player while even rows favour the second, because alternating play determines which side will eventually fill a given cell.

Frequent errors

The classic error is focusing on your own line and missing that the opponent already has three connected. Scan for their threats before each move — it takes a couple of seconds and prevents most losses — and scan horizontally, vertically and along both diagonals, since diagonal threes are the ones most often overlooked. Another frequent slip is filling an outer column casually. Edge columns carry the least connecting value, and a wasted move on the rim usually means handing over control of the centre, so unless you are defending, the outermost two columns should be left alone in the opening. The third mistake is calculating only your own next move without the reply. Four in a Row demands at least three plies: I play here, they answer there, and then what do I have. Single-ply thinking readily produces moves where your threat is blocked by a move that creates a threat of its own. The fourth is beginning to defend only once a double threat has formed, by which point it is generally too late — a completed double threat has no answer and must be prevented one move earlier.

Who it's for

Good for anyone who wants a three-to-five minute game with minimal rules and real strategic depth. The rules fit in a single sentence and children can play, yet the hard difficulty calculates multi-move threats and stays challenging for adults. The game is also completely solved mathematically: in 1988 James Allen and Victor Allis independently proved that on the standard seven-by-six board the first player wins with correct play by opening in the exact centre. Playing with that in mind changes the experience — as the first player, every inaccuracy is the surrender of a theoretically won position. It also makes an excellent introduction to logical thinking, since double threats, positional value and forced defence all carry over to other board games while Four in a Row presents them with unusual clarity. Wins and games played are recorded on your device with no account required.

Feature highlights

Three computer difficulties are available and switchable at any time, with the hard level actively calculating multi-move threats and attempting to build double threats. The record panel tracks wins and total games separately, and having both figures lets you judge your long-term rate rather than remembering only the last few games. The status line always states whose turn it is, showing a thinking notice while the computer works so you do not mistake the pause for a frozen screen or a missed input. Each column has its own drop arrow with separated tap areas, which prevents mis-taps on neighbouring columns — particularly important with seven columns side by side on a narrow phone screen. Discs fall with an animation so you can see exactly which row they settle in without counting. The result dialog distinguishes wins, losses and draws with a short comment, such as a reminder to block your opponent after a loss. A restart button is always available and the language button switches between Traditional Chinese and English instantly.

Controls and match records

Click or tap the arrow above a column to drop your disc — that is the entire control scheme, identical on desktop and phone, with no keyboard and no dragging. The arrow above a full column is disabled and does not respond, so an illegal move is impossible. Because gravity decides the landing row, your only decision is which column, which keeps the control burden minimal and leaves your attention for calculation. A restart button is available at any point rather than only once the game is decided. Wins and games played are stored locally in your browser and survive refreshes and restarts; there is no account system, the data never leaves your device, and nothing is uploaded to any server. Clearing browser data removes the record. The language button switches between Traditional Chinese and English immediately, including status prompts and result comments. After loading, the game plays offline.

Rules Q&A

Reviewed by the PocketJoy game-testing team · Operated by Long-Term New Media Limited · hklongtermad@gmail.com