a = LEFT, s = RIGHT, d = DROP, SPACE = StartGame, p = PAUSE

The objective of this game is to arrange the falling tiles into horzontal, vertical or diagonal lines of three tiles or more.
Tiles can be arranged by catching them on the paddle and then dropping them into the appropriate column.
Diagonals score more than horizontals or verticals.
Combine of horizontal, vertical and diagonals to score highly.
Tiles must not build up above the horizontal line. A life is lost for each tile that falls into a column that already contains five tiles.

The source.