Halo 3 — the much anticipated followup to the bestselling Halo 2 video game — is expected to arrive on store shelves on Sept. 25, Microsoft Corp. announced Wednesday.

The first-person shooter is the latest edition to the popular video game franchise and a key offering for Microsoft's Xbox 360 console.

"In terms of great exclusive content this is the biggest weapon that we have," said Shane Kim, corporate vice-president for Microsoft Game Studios.

Players of the game control Master Chief, an armour-clad human soldier fighting off alien hordes in both single-player and multiplayer battles.

Microsoft is hoping the game will do even better than Halo 2, which the company claims sold $125 million US within the first 24 hours of its release in 2004.

A "beta" version of Halo 3's multiplayer game is already being offered to consumers through June 6, but the single-player game has so far been kept under wraps, Kim said.

Halo 3 will be available in three versions, a standard edition costing $59.99, a limited edition version featuring information on the making of the game for $69.99 and a "legendary edition" packaged in a metal helmet like the one worn by Master Chief.

The game is an important differentiator for Microsoft's Xbox 360, as it is the only console that has the game. The Xbox 360 has sold over 10.5 million units but faces competition from both Sony's Playstation 3 and Nintendo's Wii, both of which were released last November.

PC and Mac versions of the original Halo are already available, however, and a PC version of Halo 2 is expected to hit stores on May 22.