PortalZ

PortalZ Website
Download PortalZ: The 2020 Slice

PortalZ is my map pack for Portal. Not all levels have been released, but the final version will contain 20 test chambers featuring normal Portal game elements as well as some elements not included in the game, such as Thermal Discouragement Beams and Gravity Manipulation Fields.

Most levels were designed around 2008-2009—before much was known about Portal 2. Thermal Discouragement Beams were added when it was announced Portal 2 would include lasers, but because there was no footage of players interacting with the lasers, the ones in PortalZ behave differently.

More information and download details are on the PortalZ website. There are also more screenshots of several test chambers and commentary on the design and development process.