Microsoft has made a killing with its Xbox Live Arcade, a download-only service packed with $10 games. These titles are smaller than the ones on Best Buy's shelves yet beefier than the Flash games you kill time with on your web browser. And boy, do these little games sell; that's why Sony and Nintendo stole the idea for their own systems.

Until this week, MS didn't have its own Live-only game-making group, choosing instead to buy up other designers' wares. Microsoft Game Studios Live, the new hometown studio, debuts this week by allying with the makers of South Park to make the cartoon's first good video game tie-in.



South Park Let's Go Tower Defense Play! won't blow minds, but it's breezy, amusing, and portrays the animated murders of legions of South Park's “villains”: hobos, hippies, old people, etc. Oh, Libertarian humor.

Like most games with the “tower defense” label, the object is to wipe out mobs of invaders by setting up little turrets on a large field. The challenge comes when more and different invaders pop up on the screen, requiring tower swaps, barricades, and other tricks.

SPLGTDP twists the formula by upping the action ante and adding more players. Instead of aiming a mouse cursor at the field, you run South Park's kids around to build towers, throw snowballs, and pick up invaders' pocket change. Hence, playing with your pals helps—even people who are game-shy. Only one player need worry about strategy on normal difficulty; everyone else can muck around by throwing snowballs and grabbing coins. Toss in South Park's sense of humor, complete with original, uncensored dialogue, for flavor.

'Sfun! 'Scheap! Again, it's a bit by-the-book---especially for gamers who'd rather play free web-browser versions of tower defense games---but this could've been a redundant cash-in that happens to have jokes about Kenny being poor. The twists here are smart, especially for getting four players into the tower defense action at once. Good start, MGS Live.