Your goal is to remove all tiles from the board. To remove tiles you need to match two similar tiles which are uncovered. A tile is uncovered if it is top of all other tiles or there is no other tile, around the selected tile, at more height.
You can play Easy, Medium or Hard mode of game. Easy mode has 32 different tiles. Medium mode has 48 different tiles. Hard mode has 64 different tiles. You will have unlimited layouts in each mode of the game and as the levels move, the complexity with increment in number of tiles. You also have choice to select custom number of tiles to start with.
If you find it too complex to find a pair of match, game will help you there. Hint button, at bottom right corner, will show you possible matching pairs of tiles.