Four multiplayer maps and a variety of game modes are included. However, everything won't be available initially. Instead, the various modes and multiplayer maps will be slowly rolled out across the next two weeks.

To download and play the 1.15GB beta, simply choose "Play the Beta" from the main menu of Halo 3: ODST's "Campaign Disc" and follow the on-screen instructions. However, do note that you'll need an Xbox Live Gold account to play the beta online.

In celebration of the beta's availability, publisher Microsoft issued an educational new trailer starring Aisha "yup" Tyler (The Santa Clause 3, Archer), which, alongside our impressions, should help you get acclimated while waiting for the beta to download:

The last entry in the sci-fi shooter series developed by creator Bungie, Halo: Reach will be available exclusively on Xbox 360 this fall. The next game out of Bungie will be set in an all-new "action game universe" and will hit "all platforms" via publisher Activision.