Microsoft's week-long Ultimate Game Sale for Games on Demand content makes its opening pitch today, and first up to the plate is Master Chief of the Halo Space Marines. We'll let you be the judge of whether or not the green giant knocks it out of the park with today's offers.

Three games slide down from $29.99 to $9.99 in the form of Halo 3, Halo: Reach, and real-time strategy black sheep Halo Wars - at the time of writing Wars is still $29.99, but Microsoft will probably fix that soon enough. It's not quite as big a discount for the Chief's most recent adventure; Halo 4 shifts its price to $39.99 for a 33 percent discount.