Z Chamber 05 Developer Commentary

[ZC05, entry]
This chamber was originally one of the ones that implemented a different game in Portal—specifically, the ball-rolling game Labyrinth.  Unfortunately, every method I tried of letting the player control the maze had too much of a delay without more complex scripting, and it was generally not fun, so I ended up scrapping it entirely and designing a replacement level that still used ball-rolling, but felt much more like a Portal level.