Twenty48 2048 app for iPhone and iPad

Twenty48 2048 is played on a simple 4×4 grid, with numbered tiles that slide smoothly
when a player swipes the screen in any direction. Every turn, a new tile will
randomly appear in an empty spot on the board with a value of either 2 or 4.
Tiles slide as far as possible in the chosen direction until they are stopped by
either another tile or the edge of the grid. If two tiles of the same number
collide while moving, they will merge into a tile with the total value of the
two tiles that collided. The resulting tile cannot merge with another tile again
in the same move. Higher-scoring tiles emit a soft glow.
A scoreboard on the upper-right keeps track of the users score. The users
score starts at zero, and is incremented whenever two tiles combine, by the
value of the new tile. As with many arcade games, the users best score is
shown alongside the current score.
The game is won when a tile with a value of 2048 appears on the board,
hence the name of the game. After reaching the target score, players can
continue in a sandbox mode that continues beyond 2048. When the player
has no legal moves (there are no empty spaces and no adjacent tiles with the
same value), the game ends.