What really set Portal 2 apart from the first game was its clever use of gels, each providing new ways to zip around a level (and occasionally stump the player). And now you can own some of your very own.

With Portal 2's arrival, lemons replaced cake as the game's edible meme. (If you don't know what I'm talking about, read up here) So before this one is totally played out, let's acknowledge one of its more creative applications: these prop lemon hand grenades, by flickr user ammnra.