2048

1. Swipe on a touch screen, or press the arrow keys on a keyboard, to slide every tile in that direction.
2. When two tiles with the same number meet, they merge into one tile with double the value.
3. After each move a new 2 or 4 appears in an empty square.
4. Keep your biggest tile in one corner and build a chain of smaller tiles next to it.
5. Reach the 2048 tile to win, and keep playing for a higher score if you like.
6. The game ends when the grid is full and no merge is possible; press New Game to start again.

2048 is the sliding number puzzle that took over phones and browsers in 2014, and this is the classic version. The board is a 4x4 grid that starts with two tiles. Every move slides all the tiles as far as they can go in one direction, and when two tiles with the same number touch, they merge into one tile worth their sum: two 2s make a 4, two 4s make an 8, and so on. After each move a new 2 or 4 appears in an empty square. The goal is to keep merging until you make a tile worth 2048, while the grid slowly fills up. If no move is left, the game is over.

The game was written by Gabriele Cirulli, a 19-year-old Italian developer, over a single weekend in March 2014. He shared the code for free, millions of people played it within days, and countless versions followed. Part of its appeal is the math hiding inside it: every tile is a power of two, and 2048 is 2 multiplied by itself eleven times. To reach it you need to merge the equivalent of 1,024 starting 2s, so careful planning matters far more than speed.

The best-known strategy is to pick a corner and keep your largest tile there. Build a chain of decreasing tiles along one edge, such as 256, 128, 64 and 32, so that each new merge rolls toward the corner. Try to use only two or three directions and avoid the move that would pull your big tile out of its corner. When the grid gets crowded, merge small tiles first to open space. Your score and best score are shown above the board, and New Game starts a fresh grid whenever you want another try.