Play Pentrix on freetetris.biz. It is a cool free online game in which you have to complete horizontal lines and make them disappear from the screen. This is not an ordinary Tetris game, because the Tetris shape contains four segments, while the pentrix has five segments in each shape. Imagine the difference and see how much harder it is. You even have three modes, in which the easiest is the Puzzle mode where you control the time and shapes, but you will find out that itis still bit hard to complete. Arrow keys to move left, right, rotate and drop down faster. Pentrix is the challenge, go for it!