🧩 数独游戏Sudoku
在线数独游戏：简单、中等、困难、专家四种难度，每道题都保证唯一解；支持笔记（候选数）、冲突高亮、提示、撤销和计时，自动保存进度。Play Sudoku online with four levels — easy, medium, hard and expert — and every puzzle has exactly one solution. Pencil notes, conflict highlighting, hints, undo and a timer, with progress saved automatically.
点格子再点数字填入；打开「笔记」后填的是候选数。键盘：方向键移动，1–9 填数，N 切换笔记，0/Backspace 擦除，Ctrl+Z 撤销。Select a cell, then a number. With Notes on, numbers go in as pencil marks. Keyboard: arrows to move, 1–9 to fill, N notes, 0/Backspace erase, Ctrl+Z undo.
玩法说明与常见问题How to play & FAQ
「数独游戏」怎么玩？How do I play Sudoku?
在 9×9 的格子里填入 1–9，使每一行、每一列和每个 3×3 宫内的数字都不重复。选中一个空格，再点下方数字（或按键盘数字键）填入；不确定时打开「笔记」记下候选数。Fill the 9×9 grid with 1–9 so that every row, column and 3×3 box contains each digit once. Select an empty cell and tap a number (or type it); switch on Notes to pencil in candidates when unsure.
四种难度有什么区别？How do the four levels differ?
简单 40 个已知数、中等 33 个，这两档只靠“唯一候选数/唯一位置”就能一步步解出；困难约 28 个已知数；专家只保留 22–28 个已知数，需要更高级的推理技巧。Easy gives 40 clues and medium 33 — both can be solved with singles alone. Hard has about 28 clues. Expert keeps only 22–28 clues and needs more advanced techniques.
题目一定有唯一解吗？Does every puzzle have a unique solution?
是的。题目在你的浏览器里随机生成，每去掉一个数字都会用求解器验证仍然只有一个解，所以可以完全靠推理解出，不需要猜。Yes. Puzzles are generated in your browser, and every removed clue is checked with a solver so exactly one solution remains — you never need to guess.
「提示」和「标出冲突」怎么用？How do hints and conflict highlighting work?
「标出冲突」会把同一行、列或宫里重复的数字标红；「💡 提示」会把选中格（或最容易的一格）直接填上正确答案。使用提示的局不计入最佳用时。Show conflicts marks repeated digits in a row, column or box in red. 💡 Hint fills the selected cell — or the easiest open cell — with the correct digit. Games where you used a hint do not count towards your best time.
进度会保存吗？Is my progress saved?
会自动保存在浏览器本地，关掉页面再打开可以继续；各难度的最佳用时也保存在本地，不会上传。Your game is saved automatically in your browser so you can come back to it; best times per level are stored locally too. Nothing is uploaded.
「数独游戏」免费吗？需要下载吗？Is Sudoku 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.