Portal is a skill game.
In this game you become a boy who escapes form one house to the other house.
Your target of this game is to arrive at the exit by creating entries with your shoot.
You can move your mouse to aim at the wall to create entries, and click your left mouse button to shoot, you can press the Left or Right arrow key to move left or right, press the up arrow key to jump, press Down arrow key to move down.
Attention, for one round, you can only make 2 times of shoot, after shooting, you will see one yellow and one blue entry, you can go into the one which is near you, and go out form the one which is far away from you.
Attention, you can make many rounds of shoot until you arrive at the exit, be careful you can only shoot on the wall and ceiling which is white or gray.