You wake up in Aperture Science where you have been chosen to test the new Aperture Science Multiversal Traveling Device (ASMTD) in Unit37, and for research you have been given a research core named E.L.I.Z.A, but because the portal became unstable you have been traped in another dimension and need to escape the facility but to escape it you will need to find a exit elevator with the help of E.L.I.Z.A, but remember it is possible that you may not be alone...
This is a demo of the first level in the 2nd chapter of Aperture: Unit37