🔲 数字推盘Sliding Number Puzzle
在线数字推盘（15 数码）游戏：3×3、4×4、5×5 三种大小，每局都保证可解；点击、滑动或方向键移动方块，可一次推动一整行，统计步数和用时并记录最佳。Play the sliding number puzzle (15-puzzle) online in 3×3, 4×4 or 5×5 — every shuffle is guaranteed solvable. Click, swipe or use the arrow keys, slide whole rows at once, and track moves, time and personal bests.
点击与空格同一行或同一列的方块，会把中间的方块一起推过去；也可以在棋盘上滑动或用方向键 / WASD（方块朝按键方向移动）。Click a tile in the same row or column as the gap to slide everything between; or swipe on the board, or use the arrows / WASD (tiles move in that direction).
玩法说明与常见问题How to play & FAQ
「数字推盘」怎么玩？How do I play Sliding Number Puzzle?
把打乱的数字方块按 1、2、3……的顺序从左到右、从上到下排好，空格留在右下角。每次只能把空格旁边的方块滑进空格。Put the shuffled tiles back in order — 1, 2, 3… left to right, top to bottom — with the gap in the bottom-right corner. Only tiles next to the gap can slide into it.
为什么保证有解？Why is every shuffle solvable?
一半的随机排列是无解的（例如只交换了 14 和 15）。打乱时程序会检查逆序数的奇偶性，只给出可解的局面。Half of all random arrangements are impossible (for example, with just 14 and 15 swapped). The shuffle checks the permutation parity and only deals solvable boards.
有什么解题技巧？Any solving tips?
先排好第一行，再排第一列，问题就缩小成更小的推盘；最后两行用“转圈”的方法一对一对地放好。Solve the top row, then the left column, reducing it to a smaller puzzle; finish the last two rows pair by pair by cycling tiles around.
撤销算步数吗？Do undos count as moves?
算。撤销会退回上一步，但步数加 1，避免刷成绩。Yes — undo restores the previous position but still adds a move, so records stay honest.
「数字推盘」免费吗？需要下载吗？Is Sliding Number Puzzle 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.