Chell wakes up to find herself in an antiseptic, white, test subject environment only to find that a megalomaniac, test-obsessed artificial intelligence wants her to run tests. Using the Portal Gun to bend the laws of physics, players must pass the increasingly hazardous trials of GLaDOS.

In Portal, players are presented with a unique story-driven puzzler in which they must use their wits and reflexes to pass ingenious and dangerous tests.