2048 rules

The basics

The game starts with two tiles, each a 2 or a 4.
Swipe: every tile slides that way until it hits a wall or another tile.
Two equal tiles that collide become one tile of double the value, and that value is added to your score.
After every move a new tile appears on a free cell: a 2 in 90 % of cases, a 4 in 10 %.
If a swipe changes nothing, it is not a move and no new tile appears.
When there are no free cells and no equal neighbours, the game is over.

The tricky cases

A tile merges only once per move, and merging starts from the wall you are moving towards. Examples for a move to the left (_ is an empty cell):

Before	After	Why
`2 2 2 2`	`4 4 _ _`	Two pairs: not 8, the new 4s cannot merge in the same move
`4 2 2 _`	`4 4 _ _`	The new 4 does not merge with the old 4
`2 2 4 _`	`4 4 _ _`	The new 4 does not merge with the next 4 either
`2 2 2 _`	`4 2 _ _`	The pair nearest the wall merges first
`2 _ _ 2`	`4 _ _ _`	Empty cells in between do not matter
`8 4 4 8`	`8 8 8 _`	The resulting 8s can merge on the next move
`2 4 2 4`	`2 4 2 4`	Nothing changed, so no new tile appears

Moving right mirrors this: 2 2 2 _ → _ _ 2 4.

How the score works

Each merge adds the new tile’s value to your score: 4 + 4 = 8 gives +8. A single 2048 built only from 2s is worth 20,480 points, because every merge on the way scores as well. Some 4s arrive ready-made, so the real figure is a little lower.

How high can a tile go

The theoretical limit depends on the board: building 2^k needs at least k−1 tiles on it at once. Hence:

Board	Cells	Highest tile
3×3	9	1024
4×4	16	131072
5×5	25	67108864
6×6	36	137438953472

That is why 2048 cannot be reached on 3×3: the goal there is 256.

After 2048

The game does not stop at 2048: a Continue button appears and you can keep scoring. Your score goes on the leaderboard when the game ends or when you start a new one.