Set between the events of “Halo 3” and “Halo 4,” “Halo: Spartan Assault” explores the first missions of the Spartan Ops program and dives deeper into the backstory of Human-Covenant wars. Play through the eyes of either Commander Sarah Palmer or Spartan Davis stationed aboard the UNSC Infinity as they fight in never-before-seen battles against Covenant forces.

With 25 unique missions featuring unrivaled action and intensity, the single-player experience allows you to compete against friends in Leaderboards or hone your skills with Weekly Challenges. Replay the missions to collect more than 40 in-game Achievements and Medals.

For fans who already have a prospering Spartan career aboard the UNSC Infinity, “Halo: Spartan Assault” lets you earn experience points (XP), all-new Achievements, and emblems for your “Halo 4” Spartan, with additional integration features available after launch.

Operation Hydra adds five all-new missions for fans to battle through, including new achievements on Xbox Live.

Rejoin Spartan Sarah Palmer as you intercept a haunting alien signal after the destruction of planet Draetheus V, and follow the signal to the core of the planet’s moon where you’ll discover its terrifying source. Fight with Palmer and embark on a series of new missions and new environments as you try to unravel a mystery that hits surprisingly close to home.

The expansion also adds support for wired Xbox 360 controllers, enabling you to control Spartan-IV soldiers via the familiar Xbox peripheral on Windows 8 PCs and tablets. In addition, power weapons previously only available via in-app purchase can now be bought using XP.

Operation Hydra, will be available for digital download on August 29.