Aperture Science is a secret weapons research organization in competition with Black Mesa. Chell is a test subject at the "Enrichment Centre" facility who awakens to find a A.I. construct called GlaDOS requiring some tasks to be completed. They are testing the Aperture Hand-held Portal Device (aka Portal Gun) which is able to create portals in space, allowing Chell to move from one point to another without actually crossing the distance. Chell is promised cake should she be able to overcome the obstacles and perform the necessary tests.