Tetris originated in Russia and was never patented. Its name comes from the Greek word tetra or ¨four¨. It's a -complex- puzzle game in which various shapes each made of four squares are falling down a wall. The user turns -those- pieces around and moves them -lef- or right in order to arrange them on top of the other. When a solid line of squares is made from edge to edge, the line dissolves and all the pieces move down by one square. When the lines dissolve points are won, when the wall fills up the game ends.