🔴 四子棋Four in a Row
在线四子棋（重力四子棋）人机对战：7 列 6 行竖直棋盘，棋子落到最底下，横、竖、斜连成四子即胜；三档电脑难度，困难模式几乎不失误，可选先后手或双人对战，支持悔棋。Play four in a row (connect-4 style gravity game) online: drop discs into a 7×6 grid and line up four horizontally, vertically or diagonally. Three computer levels — Hard almost never slips — play first, second or two players, with undo.
点击某一列落子（棋子会掉到该列最底部）。键盘：←→ 选列，回车/↓ 落子，或直接按 1–7；U 悔棋。Click a column to drop a disc to its lowest free spot. Keyboard: ←→ choose a column, Enter/↓ drop, or press 1–7; U undo.
玩法说明与常见问题How to play & FAQ
「四子棋」怎么玩？How do I play Four in a Row?
双方轮流把自己颜色的棋子投入 7 列中的任意一列，棋子会落到该列最下面的空位。谁先在横、竖或斜线上连成 4 个同色棋子谁就赢；42 格下满还没人连成则平局。Players take turns dropping a disc into one of the seven columns; it falls to the lowest empty slot. The first to line up four of their colour horizontally, vertically or diagonally wins; if all 42 slots fill with no four, it is a draw.
先手有优势吗？Does going first help?
有。理论上先手在正中间落子并且下得完美时必胜，所以困难模式下你执先手更有机会，执后手要特别小心。Yes — with perfect play the first player wins by starting in the centre column, so against Hard you have the best chances going first.
电脑会犯错吗？Does the computer make mistakes?
简单难度常常随手落子，只会偶尔堵你；中等会看 6 步；困难会在后台搜索到很深，很少犯错。Easy often plays at random and only sometimes blocks; Normal looks six moves ahead; Hard searches very deep in the background and rarely errs.
和五子棋有什么区别？How is this different from gomoku?
四子棋棋盘是竖起来的，棋子受“重力”只能落到每列底部，只需连成 4 个；五子棋可以下在任意交叉点，需要连成 5 个。Here the grid stands upright and discs fall to the bottom, and you need only four; in gomoku you may play any intersection and need five.
「四子棋」免费吗？需要下载吗？Is Four in a Row free? Do I need to download anything?
完全免费，无需注册、下载或安装，打开网页就能玩，手机、平板和电脑都支持；游戏完全在你的浏览器本地运行，不会上传任何数据。It is completely free with no sign-up, download or install — just open the page on a phone, tablet or computer. The game runs entirely in your browser and nothing is uploaded.