Speaking of the devil…did you knew that there’s a fan-made free flash version of Portal?
This flash version has 40 levels, each of one offering excitement and the possibility to think of a solution.
We have lots of elements that can be found in the game [the boxes, the energy balls, the impenetrable walls]. So people, can you reach the last level? See how good you really are by following the link below. This game is awesome so enjoy!