Rockstar Games has made an insane amount of money off "Grand Theft Auto." And the "GTA" brand has such cachet that you could slap it on anything and make a bundle.

"GTA" kart racing? "GTA" wrestling? Rockstar deserves credit for not trying to squeeze every last penny out of its premiere franchise.

Instead, the developers have taken the series in fresh directions, and the style, execution and ambition of 2008's "Grand Theft Auto IV" won over some of Rockstar's harshest critics.

This year has already seen the release of two original "GTA" adventures — and each one impressively expands on the studio's distinctive vision.

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—"Grand Theft Auto: Chinatown Wars" (Rockstar, for the Nintendo DS, $34.99): Shortly after the release of "GTA IV," Rockstar announced its intention to cram the sprawling Liberty City into a dinky DS cartridge.

Most of us were skeptical, but darned if the studio hasn't pulled it off. The view is different — you see the city from the top down rather than from street level — but the mighty metropolis is back in all its sordid glory.

The protagonist of "Chinatown Wars" is Huang Lee, who has flown from China to avenge the death of his father, a Triad leader.

Huang's mission requires getting close to the men who want to take over his dad's old job, so the early parts of the game involve running various errands: recruiting new members, killing rivals and, of course, stealing cars.

Beyond the main plot, there's a remarkable variety of things to do. You can race, of course, or you can pick up odd jobs or go on killing sprees. I wasted hours running around trading drugs with dealers all over town.

The minigames — like hotwiring cars or creating Molotov cocktails — make clever use of the DS touchscreen.

Indeed, the whole of "Chinatown Wars" is a demonstration of how to make an exemplary handheld game out of a series designed for a larger screen. Four stars out of four.

—"Grand Theft Auto IV: The Lost and Damned" (Rockstar, for the Xbox 360, $20): Similarly, "The Lost and Damned" is a lesson on how to create fresh add-on content for old games.

It builds on "GTA IV" with an original, 10-hour solo campaign as well as some new multiplayer modes — as much material as you get in many full-priced games.

The primary weakness of "Lost and Damned" is its story, which revolves around a power struggle among the leaders of a biker gang.

The hero, Johnny, is so unappealing that I really missed "GTA IV" hero Niko Bellic — especially when Niko popped up in the occasional cameo.

Still, the gameplay remains rock-solid and the mayhem is just as explosive, making this a must-buy for fans of last year's smash. Three stars.