Every now and then, Halo game fans grouse that they have to pay $10 to get three additional maps with every new multiplayer map pack that Bungie comes out for the Halo: Reach game for Microsoft‘s Xbox 360 video game console. Then they go and spend a million hours playing it nonstop until they can pretty much memorize every detail of the map and eviscerate rivals with ease.

That cycle is about to begin anew with the Halo: Reach Defiant Map Pack that Microsoft released today. But instead of trashing Bungie, those grudging fans will have to sling mud at Microsoft. Microsoft’s 343 Industries game studio and the Certain Affinity map pack team were responsible for getting this map pack out the door. It is the first official act of 343 Industries, as Bungie, the development studio that created the lucrative Halo series, moves on to making other game worlds.

As we noted in our past stories on map packs, the task of making one isn’t nearly as big an undertaking as a brand new game. But it’s important in generating sequel revenues, and it reassures fans that Microsoft will focus a lot of resources on the care and feeding of the Halo franchise, which has generated well above 40 million units and nearly $2 billion in sales. Halo fans have played more than 3.3 billion hours on Xbox Live. You have to figure that this new map pack will generate hundreds of millions more hours of entertainment for gamers. It’s all part of the plan to generate Halo revenues for years to come, in between big games.

And map packs are a nice defensive measure in the video game industry these days. If fans are playing your map pack, they’re not playing a new game from a rival or another map pack, like one from Activision Blizzard’s Call of Duty series. So the map pack has to be designed just right. It can’t be too easy for players to master, but it also has to be challenging.

Frank O’Connor, head of 343 Industries, told us in a video interview that you often can’t trust gamers’ words when they describe what kind of map pack they would like you to create. That’s because the way they say they play often differs from the data collected from the game that shows how they play. The analytics are critical in making sure that map packs are balanced and fun.

The Halo Reach Defiant Map Pack is the second for Halo Reach, the Xbox 360 game that launched last September as the last Bungie-created installment of the Halo universe. The map pack has the first-ever Firefight mode for Halo Reach as well. That’s where you fight cooperatively with fellow human players against masses of computer-controlled enemies who keep coming at you until you all die. That’s an appropriate addition, considering the storyline of the losing battle from the Halo Reach game.

The maps include Condemned, which takes place above a massive space station in orbit above the planet Reach. A lot of the fighting centers around a multi-level central ring (pictured at top) where you can jump high into the air and shoot your enemies either above or below you.

It also includes Highlands, a military training space set in a wooded area on Reach. It’s a big map where players can engage in massive 16-player battles. Lastly, there is Unearthed, a Titanium mine and refinery on the planet where you can ride around in vehicles such as the Warthog.

Halo is now in its tenth year. If Microsoft plays this right, it will still be around in its 20th year. The map pack costs 800 Microsoft Points (yes, $10!) to download on Xbox Live.