2048

2048 is played on a 4×4 grid. Every move slides all tiles to one side, and two tiles showing the same number merge into one worth double. Reach a tile showing 2048 and you have won — though most people carry on well past it.

What makes it hard is not the arithmetic. After every move a new tile appears at a random empty square, so the board fills up whether you are making progress or not. Once it is full and no two neighbours match, the game is over. The whole skill is keeping your options open.

Each merge adds its own value to your score, so a single 512 tile is worth far more than the sum of the small merges that built it. Undo is available for the last move, and your best score is stored in your browser.

1. Slide the whole board in one of four directions. Every tile moves as far as it can that way.
2. Two tiles with the same number merge into one worth double. A tile can only merge once per move, so four 2s in a row become two 4s, not one 8.
3. After each move a new 2 or 4 appears at a random empty square — a 2 nine times out of ten.
4. Reach the 2048 tile to win. You can carry on afterwards for a higher score.
5. The game ends when the board is full and no adjacent tiles match. Undo reverses your last move if you want to try a different line.

Desktop: use the ← ↑ ↓ → arrow keys or W A S D to slide the board. A direction that would not move anything is ignored, so you cannot waste a turn by pressing into a wall.

Mobile and tablet: swipe anywhere on the board. A swipe has to travel about 24 pixels to register, which stops taps and small drags from triggering a move by accident.

The Undo button below the board reverses your last move, including the tile that spawned. It only stores one step, so it is for recovering from an obvious mistake rather than exploring several lines.

• Pick a corner and never leave it. Keep your biggest tile in one corner and only ever slide in the two directions that keep it there. Almost every strong game is built on this.
• Build a descending row along one edge. With your largest tile in a corner and the row beside it decreasing in size, merges cascade naturally instead of needing to be set up.
• Avoid the fourth direction. If your big tile sits bottom-left, use left, down and right — pressing up will usually pull it out of the corner and the position collapses.
• Merge small tiles early. Loose 2s and 4s scattered across the board are what fill it up. Clear them while there is still room.
• Look at where the new tile can appear. Before a move, notice how many empty squares you will be left with. Dropping to one or two is when runs end.