An old, dusty sign says Still Creek’s population is 753, but those were warm bodies. With the undead apocalypse in full swing, the small town is crammed with shuffling corpses, all starving for a piece of motocross champ Chuck Greene and his daughter, Katey. They’ve been stranded here on their way to Fortune City (aka Vegas) — the setting of the upcoming Dead Rising 2 — and their bad luck is our sinful entertainment.

At just $5, this downloadable prologue is a great warm-up for the zombie-slaying sequel, offering a five-hour taste of its wild mayhem. With Katey stashed at a safehouse, Chuck scours the town for five parts so he can assemble a motorcycle and drive them the hell out of there. As you roam the streets and the local casino, hardware store, and other shops, hordes of undead are just begging to be shot, chopped, maimed, and destroyed.

We love the new ability to craft an extreme weapon out of a couple of items: you can sample a handful of the full game’s countless possibilities — including a Spiked Bat (baseball bat + nails) and head-pulping Drill Bucket (bucket + electric drill) — and discovering new combos and unleashing gonzo gear like the Air Horn (pylon + spray paint) is a blast. Some of Dead Rising’s irritating game mechanics, like its horrendous aiming and movement while wielding a gun, are much improved, and the sea of groaning ghouls has never looked better.

Dead Rising’s hideous save system has been tweaked, too: you still save at bathrooms, but with three save slots, you no longer risk a save-game from which you can’t progress. Case Zero isn’t without weirdness, though. You have only one full day to do everything: build the bike; escape town before the military arrives and seizes the infected Katey; see all the sights; and rescue the 10 or so survivors, which is the best way of earning the prestige needed to boost Chuck to level 5. (Your level carries over to Dead Rising 2, letting you start the game with elevated skills.) Problem is, it’s virtually impossible to do all this stuff within one in-game day, so multiple playthroughs are pretty much a given. Repeating such a short game isn’t bad, but why not just give us two days for everything, without the needless contrivance? We’d rather mash zombies without interruption.

On Xbox Live Marketplace

+ Piles of zombie-stompin' fun, with a compelling premise.

+ Meaty intro to full game for a bite-size price; tweaked mechanics; leveling carries over to full game.

- Even with more save slots, multiple playthroughs aren't really optional.

? Why is Chuck stupid enough to leave the keys in his truck?

8.5