Figured I'd say this, in the Cortana level, as long as can get all the cloaks while running as fast as you possibly can, you can skip the WHOLE level up to the part where you find Cortana and the enemies glitch (won't attack often). After that it's a cake-walk. BUT!!!! That's totally lame and I don't recommend that anyone do it. However, this method will probably result in beating the level under 20 minutes guaranteed. This HAS to be the speed run method. PS - tried it myself and died at the VERY last part - after I get Cortana. If anyone is up for it knock yourself out 'cause it just got a HELL of a lot easier.