Playing a game of “Halo” with Justin M. Craig ’07 is a risky endeavor.

“Friends are made and lost in the course of a ‘Halo’ game,” said Craig, who plays the video game “religiously” for two hours everyday.

Yesterday Harvard’s biggest fans of the video game, in which users try to defend the earth from aliens, joined enthusiasts across the nation in celebrating the release of “Halo 2,” the successor to “Halo: Combat Evolved.”

The Washington Post has called the video game’s release “the biggest launch in entertainment history,” expected to bring in over $80 million in sales. The original installment was immensely popular, selling over five million copies since its release in 2001.

Roommates Stephen T. Norberg ’06 and Michael J. Finch ’06 have formed a dedicated “Halo”-playing duo. The two “Team Aardvark” members sport T-shirts and have their own website and a “Team Aardvark” group on thefacebook.com. Finch, whom Norberg described as the more intense half of Team Aardvark, was one of 1.5 million fans who pre-ordered “Halo 2,” contributing to the $75 million in pre-ordered sales for Microsoft’s Bungie Studios.

Reed C. Bienvenu ’05, who with two of his roommates headed over to EB Games in CambridgeSide Galleria half an hour before the 12:01 a.m. opening time yesterday, was nonplussed by the energy level there.

“It was pretty quiet actually,” Bienvenu said, “I thought it was going to be a rowdier group.”

In anticipation of the “Halo 2” frenzy, Bienvenu’s roommate Pat R. Griffin ’05 sent an e-mail over the Mather House open list, offering up his roommates to purchase and deliver games for $65. “Halo 2” sells in stores for $49.99. Although no one had replied to the offer by their departure time, the threesome bought two extra copies, just in case.

At EB Games in Watertown’s Arsenal Mall yesterday, over 150 people stood in the cold until just after midnight, when over 6,500 stores across the country, from Circuit City to Game Stop, opened their doors in synchronized celebration. The Watertown store’s Assistant Manager Jason Tavares characterized the event as a “mad dash to the doors.”

Between midnight and 2 a.m. yesterday, “Halo” enthusiasts came to EB Games in Watertown not only for the new release but to snap up anything with the “Halo” logo: T-shirts, posters and even the soundtrack.

“It’s one of those experiences you don’t really have as a gamer,” Tavares said.

He said that most customers were male, in their late 20s or early 30s.

“Of the 200 people here, probably six of them were women,” Tavares said, adding that women comprise a sizable gaming demographic, just not for “Halo 2.”

At CambridgeSide Galleria’s Best Buy, however, “no one certain group” was representative of the average “Halo” customer, according to Robby Moses, a 20-year-old media associate at the store. But the buzz was considerable there as well.

“For the past three weeks, people have been coming, wanting to know when Halo’s getting here,” Moses said. The only other video game that drew as much attention in the store was “Grand Theft Auto: San Andreas,” released last week to comparable hype, according to Moses.

Despite some customers who came in to pick up the new “EverQuest 2,” also released this week, 95 percent of business at Watertown’s EB Games yesterday centered on the game of the hour.

“Right now, it’s all about ‘Halo,’” Tavares said.