The Game Informer reveal of Portal 2 details led to speculation that new gameplay elements will follow the same path as Digipen student project Narbacular Drop (which the original Portal was inspired by). Colour me as again missing the boat, but the 2008 release of Tag (~50mb download) passed me by. It was a first-person puzzle platformer with a goal to simply navigate through levels. It’s really a tech demo, but its possibilities really highlight how to improve Portal‘s mechanics… and it just so happens its creators may now be under Valve’s employ.
The fun core of the game is manipulating surfaces through use of a paintball gun to allow jumping, speeding up your running speed, and allowing you to pull off a gravity-defying walks on any surface (like Prey‘s ceiling-traversal). The open-air urban setting (used due to the jumping component) recalls Mirror’s Edge environments but with monochrome, texture-free geometry combined with a graffiti aesthetic. Check it out if you want to see what Portal 2 may play like at year’s end.