I spent many hours as a teenager glued to my PC learning the intricacies of ‘Duke Nukem 3D’ level design.
… and this isn’t my first foray into the world of level creation. Yes, Valve had previously released a full dev kit for Portal (and if you want to see an excellent community made mod then check out Portal Stories: Mel), but this was all about the normal person with that spark of “ oh, this would be a really interesting level” about them, but not the time to invest in learning a complicated developer environment… in a roundabout way I’m trying to say that I’m their target audience. In its least fanfare presented way, it is a level editor, aimed at allowing any user to quickly an intuitively create ‘Portal 2’ test chambers, publish them to the steam workshop system, and easily subscribe to others.
The perpetual testing initiative was a clever slice of free post-launch DLC for ‘Portal 2’ released in 2012 with this cute aperture science video/octopus to go with it.