The objective is to slide numbered tiles on a grid to combine them and create a tile with the number 2048. But you can keep playing the game past that and create tiles with larger numbers.
Every turn a new tile will randomly appear in an empty spot on the board. Tiles slide as far as possible 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 the sum of them combined. The resulting tile cannot merge with another tile again in the same move.