Move with the arrow keys or WASD, or swipe on a touch screen. A move only counts if at least one tile moves or merges. Pressing a direction that changes nothing does not spawn a new tile.

After every valid move a new tile appears in a random empty cell. It is a 2 about nine times out of ten and a 4 about one time in ten.

Each tile can merge only once per move, and merging starts from the edge you are sliding towards. A row of 2, 2, 2, 2 pushed left becomes 4, 4 rather than a single 8, and a row of 2, 2, 2 becomes 4, 2.

The run ends in one of two ways: you create a 2048 tile, which is a win, or the grid fills up and no two neighbouring tiles match, which is game over. In both cases, press Play Again for a fresh board.

Every merge adds the value of the tile it creates. Merging two 8s adds 16 points; merging two 512s adds 1,024. Early merges are worth very little, so most of a finished score comes from the last few big merges.

Your best score is saved in your browser under the username you pick. If you sign in, personal bests can also sync to your account.

Pick one corner and keep your largest tile there for the whole game. Build a descending chain of tiles along one edge so that merging always cascades towards the corner.

Use three directions for almost every move. If your big tile is in the bottom-left, rely on left, down and right, and treat up as an emergency move, because pushing up can pull your large tile out of its corner.

2048 was written by Gabriele Cirulli, a young Italian developer, and released as an open-source web game in March 2014. It borrows ideas from earlier sliding-tile puzzles such as Threes and 1024, and it spread quickly because the rules fit in one sentence and it runs in any browser with no install.

Merges happen along a line, so tiles that sit in the same row or column can combine in a chain. If your biggest tile is in a corner and the next biggest sit beside it in order, one swipe can merge several tiles in a row. If your biggest tile drifts into the middle, small tiles can end up trapped on both sides of it and the board fills with values that can never meet.

Keeping the bottom row (or whichever edge you chose) full and ordered also gives you a safe direction to move when the board is crowded. A move along a full, ordered edge changes nothing there, so it cannot disturb your structure.

• Look at the whole board before every move instead of reacting to the newest tile.
• Merge small tiles early. Leaving several 2s and 4s scattered around costs you empty cells you will need later.
• Do not chase a merge if it forces the board to fill. An empty cell is worth more than a small score.
• If you are forced to break your corner rule, move the board back into shape as soon as you have space.

On a 4×4 board the largest tile that can appear is 131,072 (2 to the power of 17), but no human game gets close. Reaching 2048 is a realistic goal for a patient player. Getting there reliably is mostly a matter of discipline about the corner and about not rushing.