By Darren Waters
Technology editor, BBC News website
A trial version of the online multiplayer section for the third title in the Halo series is released on Wednesday. It is the first step in Microsoft's strategy to ensure that the Xbox 360 is the console of choice this Christmas.
Watch Halo 3 in action. This title is likely to be a 16+ game.
The game has been more than two years in development and fans pore over every snippet of information and screenshot dripped out from makers Bungie each week.
But for the next three weeks they will be able to get their hands on the online portion of the game - playing a limited number of maps with people around the world.
It is an unusual step for a console title, but reflective of just how important Halo is to Microsoft.
The first game, released in 2001, arguably saved the fortunes of the Xbox; it won countless plaudits and helped ship millions of consoles.
The second title sold an even greater number, and the online element of the game is one of the most enduring multiplayer titles with tens of thousands of players still logging on each day to play.
More than 2.5m copies of the sequel were sold on the day of release - with sales of more than $125m.
Three maps can be played in the beta trial
The franchise has been likened to a blockbuster movie and Microsoft is pitching it as one of the biggest entertainment releases of the year.
"I believe this is going to be one of the three biggest consumer entertainment events of the year, along with Spider-Man 3 and the new 'Harry Potter' book," Shane Kim, head of Microsoft Game studios, has said.
The third game is not due for release until the autumn but to keep fans' interest and kick start momentum for launch, a beta version is being released on Wednesday.
Gamers can battle online in three different maps in a number of different game types.
For the uninitiated, Halo's multiplayer is a form of virtual warfare, in which gamers use weapons and vehicles either to win team battles or to achieve strategic objectives, such as capturing flags or defending territories.
The key question, of course, is how it plays? The answer: Halo fans will not be disappointed but it is unclear if the game - on the evidence of the multiplayer alone - will win over new players.
Halo 3 makes the move to the high definition age beautifully - the game looks stunning, despite the sniping from some online critics.
A mammoth advertising campaign for Halo 3 is likely in the lead up to launch
Some of the maps are a joy to behold - hi-def textures, graphical effects and little touches such as gamers' footprints in the snow, combine to create a visual feast.
There are a few jagged edges on some of the landscapes but this is still beta code and is to be expected.
I recommend that gamers take a moment between the madness of bullets and grenades to walk down to the water on map High Ground and just marvel at the rippling tide.
The game play has been tweaked and touched up to add more depth and variety to battles.
Halo 2 was criticised for turning battles into a virtual game of scissors, paper, stone with the winner of encounters being decided by the player with the biggest gun or guns.
To compensate, Bungie has altered the balance of weapons and added the element of equipment, such as bubble shields and personal gravity lifts.
Battles can be won and lost with the drop of the shield or launching away from a tough encounter with the lift.
There are new features too, such as the ability to record a video of your online exploits and share it among friends, which could well prove to be one of the killer elements of the title.
Bungie is keeping the single player element of Halo 3 under tight wraps but fans will be hoping that lessons are learned from the sequel.
While the original Halo won awards for combining great story-telling with action, the sequel proved a little convoluted.
A mammoth advertising campaign for Halo 3 is likely in the lead up to launch, as Microsoft hopes to maximise the impact of the game in the console wars.
The Halo 3 beta might not be evidence of a killer blow, but it certainly shows promise of being able to inflict terrific damage on its rivals' aspirations.