Editor note: Some story spoilers.

The season for epic games has begun. Gamers worldwide start shooting and save the world. Epic Games‘ Gears of War 3 launches today, and it brings closure to a sci-fi shooting game series that has kept millions of fans loyal to the Xbox 360 video game console.

Gears of War 3 is one of the blockbusters of the all-important fall selling season, and it has sold more than 13 million units, or more than $780 million at retail, since its debut in 2006. It is one of Microsoft’s major exclusives for the Xbox 360 and will help Microsoft fend off rivals Sony and Nintendo in the coming months.

I’ve completed the game’s most difficult level and am glad to say that the ending to the three-part series is going to be a memorable one for Gears fans. The game introduces its first female characters among the grunts known as Gears, and it brings home a story that had gone down many different tunnels over the years.

Gears of War 3 is the kind of game that has helped magnify the coolness of brands like the Xbox 360 and Microsoft in the gaming business. Gears of War 3 should help the series ascend into the pantheon of some of the best loved and most lucrative video game franchises of all time. Like Microsoft’s Halo, Gears of War has become a cultural phenomenon, where celebrities and fans alike brag about their enthusiasm for the game.

Gears of War’s contribution to video games is that it raised the bar for “movie-like” games, since the action and the film-like sequences are seamlessly interwoven. Only a handful of blockbuster titles such as Uncharted 2: Among Thieves and Halo: Reach have delivered these kinds of experiences for gamers, where it’s hard to tell where an animated film sequence ends and the game action begins. Little did we gamers know that the purpose of the film sequences is to give the Xbox 360 hardware enough time to stream in the next bits of the 3D environment. In any case, the immersive feel of single-player campaign game is what I enjoy about the Gears games, in contrast to its multiplayer combat.

Will this game be the bestselling yet? Probably so, since there are now almost 56 million Xbox 360 consoles in the market, much more than when Gears of War debuted in 2006 and when Gears of War 2 debuted in 2008. But at the same time, video games have been in a funk this year in the U.S., with sales down in part because gamers have so many choices for content these days, such as iPads, smartphones and social networks.

If any game can overcome these cross-currents, it is a Gears of War title. The series has spawned four bestselling novels and is the subject of an upcoming film. It has given gamers a reason beyond Halo to buy an Xbox 360. And the competition has steered clear of the Gears of War 3 release. Resistance 3 debuted on the PlayStation 3 on Sept. 6 and id Software’s Rage won’t come out until Oct. 4.

Aiming for a bigger hardcore game market

As we noted in our preview story, Gears has been a tale about hope, survival, and brotherhood. The player assumed the role of Marcus Fenix, an imprisoned marine who was let loose as a last-ditch effort to save humanity. The game is a third-person shooter with a cinematic style and rivers of blood.

The violence and blood are so pervasive that it almost seems like you’re in a violent Quentin Tarantino film, such as Kill Bill. That is part of the appeal of the game, since it is so bloody it is almost comical. Add to that the swagger and the funny banter among the marines, or Gears, and you have a witty and self-aware work that holds the attention of gamers, who have been conditioned to have a sick sense of humor. The characters seem like real grunts from our own modern era, as the dialogue is full of foul language, put downs, wisecracks and comebacks. Only they have to deal with enemies worthy of the scariest horror movies.

In a brilliant piece of game marketing, Microsoft created a commercial for the original game using the depressing “Mad World” song as sung by Gary Jules. That set the tone for the relentlessly downbeat struggle that the player had to fight in a world of “destroyed beauty,” where a beautiful planet was in ruins. That video was so popular that it was watched by millions on YouTube and it multiplied the marketing budget for the game many times over.

This time, musicians Ice-T and Body Count have created an exclusive new song for Gears of War 3. The music is just a small part of a calculated marketing campaign. The overall goal is to get to as many users as possible; that’s why the game includes a more accessible casual mode.

“We’ve made the game easier to play,” Rod Fergusson, executive producer of the game, told me in an interview. “We made it more accessible with a casual game setting and a casual multiplayer mode as well. If there’s one Gears of War game you’re going to play, we want it to be this one. For everyone who hasn’t tried it yet, this is the version to try.”