It would be neat if this was just one mechanic in a bigger game but not a whole game.

it's hard to know how this mechanic would have panned out into a full scale game, as this is just a super-basic demo of the concept. I like to think that Valve would have developed it into something much grander, but i guess we'll never know. That being said, this doesn't look like it rewards the same kind of non-linear thinking that Portal does, with the solutions all being pretty obvious from the outset of each level, once the player understands the mechanics. Valve was correct to scrap this.