Portal is a puzzle game on flash-game.net in which you should use your head to get a good score. When you first see the game scene, maybe you will feel complex and start without knowing where to begin, because there are innumerable blue right angle on the brown background. But when you click anyone of the angles by your mouse, you will find it is very easy to play the game. There is a chain-reaction after your click, because through revolving, one angle will touch another angle, and the another touches the others. The objective of each level is to open the gate and advance to the next levels. To do that, you have to fill the energy bar in the upper side of the screen. Each stone disk rotation produces energy. The disks will activate themselves if the energy lines are connecting. Click on any disk and try to produce a energy chain as long as possible.