1. Portal

Guides for "Terminal Velocity"

  1. 0
    • Terminal Velocity

    You can get this achievement on Chamber 15 and a few others, but this is the one that I did it on. You just need to put a portal on the ceiling above you and one on the floor directly beneath it so that you infinitely fall through. Eventually the achievement will pop up. The link to the portion of the video where this is covered is here.