Several hundred years after Portal 2 co-op, GLaDOS is working her way through the Test Subjects from the Preservation Annexe. You are Amy, one of these Test Subjects. As you make your way through the Enrichment Centre, you encounter many new testing elements, and even visit the lower levels. But as you progress, you begin to wonder what plans GLaDOS really has for you. In ancient tests far below the Centre, which Chell might find familiar, you encounter Taylor the Core. With his help, will you ever return to the modern Enrichment Centre and defeat GLaDOS?
These chambers will be Enhancement's 'underground' track. See News for more!