RAD isn't saying how the deal to get the Cube in the game -- and out of Portal -- was struck, but it does have instructions on unlocking this tasty (like cake) triumph: "if you finish Chains of Olympus in god mode, no upgrades, and collect all the urns of power twice without dying you open up the companion cube as a hidden character." If you can muster that, we'd consider it a huge success. If you can't, at least watch what you're missing after the break.
