That’s partially because the name “The Orange Box” sounds more like some kind of citrus-scented bathroom cleanser than a video game, and partially because this [] Half-Life 2 The Orange Box - PC - Torrents Games.
If it is an XBLA game, you should not experience any issues running it from a flash drive. I had burnt out my hard drive at one point, and could only run games off of flash drives. The one snag here is that games that come with discs need the disc in the drive regardless of having had installed them or not. Now I would assume that is not the case if you purchase the game through the marketplace. Say you purchased halo 3 and downloaded it, I would figure that Microsoft has made it such that, that version, does not require a disc to play. Thus it should run from where ever it is, be it hard disc drive, flash card, or external hard drive.