“This next generation of iPhone games” has emerged, says Dean Takahashi of VentureBeat.com, because Apple has “a big market with 40 million iPhones and iPod Touches. That’s big enough to target with a fairly significant game-development effort.”

Among games with amped-up action:

•Doom: Resurrection ($10), just out, makes use of monsters created for Doom 3, developed for PC and Xbox less than five years ago. “What was a $10 million to $15 million game development” has moved to the iPhone with “minimal conversion,” says id Software co-founder John Carmack.

•Players of new sci-fi strategy game Star Defense ($6) can send challenges to one another over the iPhone or via Facebook, Twitter or e-mail, thanks to last week’s update of Apple’s operating software. “People are willing to ’snack’ on games, to experiment a little bit more,” says former Sega executive Simon Jeffery, who joined developer ngmoco last month. “There isn’t the same barrier to entry” as with traditional $60 video games.

•The smooth graphics in aerial combat F.A.S.T. (Fleet Air Superiority Training, $3) from Social Gaming Network put you into the cockpit of a fighter jet. “You are flying around in a 3-D world, shooting down other pilots from all over the world,” says SGN’s CEO Shervin Pishevar. (The game is No. 6 in sales of paid apps on iTunes.)

Apple’s App Store, launched last year with only 500 apps, now has more than 50,000, one-fourth games (some free, others 99 cents to $9.99). In addition to independent developers, top-tier publishers such as EA are bringing high-end versions of games such as The Sims 3 to the iPhone.

With the iPhone, Apple has “something that is potentially a threat” to traditional game systems, says Windsor Holden, an analyst with Juniper Research. “They are not quite console games, but they are not far off.”

iPhone game sales could hit $1 billion in the next three to four years, says SGN’s Pishevar. “This is just the beginning,” he says. “It’s just going to get better and better.”

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