Chell is released from her tiny cell and put through a series of tests involving an experimental technology. Each test requires simply that she move to the exit, like a rat in a maze. She acquires a Portal Gun for use in these tests; interestingly, the gun's masculine symbolism is subverted by the fact that it shoots portals rather than bullets. Portals are oval-shaped openings that are visually and spatially connected; go in one and you'll come out the other. The Portal Gun creates connections rather than destroying life. It is through innovative placement of these connections, or portals, that goals are achieved or enemies overcome. A psychoanalytic reading would likely conclude that the portal is an image of the female sex organs: oval and receptive, and also a metaphorical birth canal through which the protagonist is constantly being born into new trials.
Another subversion of FPS norms takes place in the presentation of conflict. The primary antagonist is an unstable artificial intelligence named GLaDOS, a maternal female construct who administers the experiments. She antagonizes you/Chell not through physical brutality but through emotional manipulation. Some of Portal's best dialogue occurs when holes appear in GLaDOS' programming while she's in the midst of especially cloying or manipulative statements. In one example, GLaDOS congratulates Chell by saying, "You, subject name here, must be the pride of subject hometown here." These malfunctions call attention to the fact that GLaDOS was programmed to respond empathetically but doesn't actually feel emotions the way a human being does. As such, she comes to represent man's attempt to construct an idealized mother figure through the cold logic of science. The resulting entity is a jumbled mess of cross-purposes and psychic detritus who attaches more value to the Portal Gun than to human life. You must outsmart, rather than outgun, this enemy to escape with your life.