Given the tech-savvy nature of video-gamers, you'd think that more games would be based on science-fictional ideas.

Sure, some of the classics — "Halo," "Metroid," "Xenosaga" — fit the mold. And designers of first-person shooters frequently look to the future to find inspiration for their ever-more-elaborate devices of destruction.

But flat-out SF is relatively hard to find.

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For comparison, look at the dozens of fantasy-inspired games that come out every month. Almost every role-playing game is a sword-and-sorcery tale, and action games more frequently involve fighting demons rather than aliens.

I'd rather fire a phaser than swing a magic wand. I'd rather pilot a starship than ride a horse. And I'd rather explore another planet than visit another medieval town.

Science fiction offers plenty of source material, and game designers have only scratched the surface.

—"Destroy All Humans! 2: Make War Not Love" (THQ (THQI), for the PlayStation 2, Xbox, $39.99): The last time we saw the bug-eyed alien Crypto, in last year's "Destroy All Humans!," he was wreaking havoc in 1950s America. Clearly he didn't succeed in his mission, because there are still plenty of "meatbags" running around when he returns in 1969.

As the adventure begins, Crypto is in "Bay City" (that is, San Francisco) trying to infiltrate a hippie cult with more on its mind than free love. Along the way he meets more `60s stereotypes, like swinging British spies and humorless KGB agents.

The comedy is fairly broad, lacking the tight focus of the original's B-movie parodies, but Crypto's surly, Jack Nicholson-like voice is oddly appropriate amid the lighthearted mayhem.

Once again, you'll have to take over human bodies to accomplish some goals, but most of the time you'll be fighting enemies and blowing things up with some groovy new weapons, like a gun that unleashes violent meteor showers.

No doubt Crypto has even more terrifying things in store when he has to contend with the Disco Era.

Two-and-a-half stars.

—"Contact" (Atlus, for the Nintendo DS, $34.99): Here's a strange and whimsical adventure from the creators of last year's strange and decidedly-not-whimsical "Killer 7."

After a spacefaring professor crash-lands on a mysterious planet, he enlists a kid named Terry to recover the fuel cells that have been scattered on the surface.

The "contact" in the title refers to some fourth-wall-breaking antics: The professor, on the top screen of the DS, talks to you — the DS player — while you tell Terry, on the bottom screen, what to do.

It's a charming gimmick, but the designers don't take it as far as they could have. Terry's explorations are pretty standard fare, mostly involving crawling around dungeons and killing monsters.

The combat itself is the worst part of the game, since all you can do is tell Terry to attack; you have no control over how he swings his weapon. It gets tedious very quickly, diminishing the goodwill generated by the wryly postmodern approach "Contact" takes to the genre.

Two stars.

—"Phantasy Star Universe" (Sega, for the PlayStation 2, $49.99; Xbox 360, $59.99): A lot of role-playing game aficionados first experienced the genre in Sega's 1987 "Phantasy Star," which deftly combined sword-and-sorcery with planet-hopping.

The franchise went online and multiplayer in 2001, alas, but the latest installment does include a solo adventure for us lone wolves. It takes place in the Gurhal System, where four races coexist on three planets — but as the game begins, an alien species attacks.

Ethan, the protagonist, is a military cadet whose search for his missing sister leads him deep into an alien conspiracy.

The story doesn't offer many surprises, and the combat is lackluster, for the most part requiring no more than rapid button-mashing. Occasionally you're treated to some beautiful interplanetary vistas, but you also spend a lot of time in drab industrial hallways.

If you have a GameTap account, go play the original; even with 8-bit graphics, it's more majestic than "Phantasy Star Universe."

Two stars.