Players booting up Portal 2 for the first time may have noticed an unexpected addition to the start-up menu. The Robot Enrichment option at the bottom of the screen leads to an in-game item store. The items allow you to customise the co-op bots Atlas and P-body with a number of different paint jobs, emote gestures, and, of course, hats! There's also a trading window which will become active in the next few days.
It looks as though certain objects can be unlocked by completing achievements, too. the one achievement item in my backpack so far, though, is marked as being un-tradeable. It seems unlikely that players will trade items that they've paid for. Perhaps there are other ways to get hold of the new items? Unlike Team Fortress 2,there's no crafting option. Yet. After the recent ARG , who knows what Valve will do next?