For 1200 Microsoft Points you can pick up Perfect Dark, the Rare developed classic was first released on Nintendo 64. The Xbox Live version of the game features online multiplayer via Xbox Live, enhanced graphics, and many other small tweaks to perfect the game play.
The single player campaign consists of 17 level based missions. You control Special Agent Joanna Dark as she tries to infiltrate and sabotage rival corporation dataDYNE. The missions range from stealth mission to assault missions. However you will spend most of your time with this game in the online multiplayer, the modes are versus, cooperative version of single player campaign or play a versus version of the single player campaign.
When this game came out it was widely regarded as the superior shooter when compared to GoldenEye, so keep that in mind that you will be playing the best shooter of that generation.