It would take about three viewings and four scraps of paper to list all the wonderfully geeky horror references found within James Gunn's Slither. Half-horror, half-comedy, and (once it gets rolling) packed to the rafters with gleefully giddy gore-splatters, this flick is made for (and by) precisely one type of moviegoer: The old-school horror geek, the ones who'll sit through a cock-eyed fright flick, smiling and intermittently elbowing his neighbor in the ribs while muttering "The Blob. Body Snatchers. They Came From Within. Night of the Creeps. The Thing. CrittersBasket Case!?? Society!?!??"

Yes, horror fans, Gunn's directorial debut (after penning Tromeo & Juliet, he wrote both Scooby-Doo flicks and the fantastic Dawn of the Dead remake) is an absolute stew of creatures, characters, and conventions snatched from a dozen easily recognizable sources. (Well, recognizable if you grew up in a video store during the 1980s, anyway...) But the young filmmaker makes the difference between "homage" and "ripoff" quite apparent, because Slither has a large and obvious streak of affection for all the flicks mentioned above, and probably a dozen more.

The setting is the grungy backwoods burg known as Wheelsy, recent landing spot of a particularly nasty meteor. Just as in the first 15 minutes of every 1950s-era sci-fi flick ever made, one stupidly curious passerby decides to poke a stick at the space rock, and the result is a needle to the chest of one unlucky dude. Grant Grant (played by Michael Rooker) is his name, and he’s not only a rich and respected Wheelsy citizen, but also husband to a willowy trophy wife called Starla. Grant begins to … metamorphosize into a decidedly unpleasant goo-machine, but Starla aims to stick by her man, regardless of the extra teeth and the rotting flesh and the... Well, Starla gives it a pretty decent shot, anway.

“To the rescue” comes newly appointed Chief of Police Bill Pardy (Nathan Fillion) and his wacky array of subordinates, most of whom end up on the receiving end of claws, tentacles, or teeth before too long … and thus begins one hellaciously sticky night in the town of Wheelsy. From here on out it's a parade of murderous slugs, shuffling zombies, and outright mayhem as the few still-human survivors do all they can to avoid the interstellar insanity.

Needless to say, this ain't Voltaire we're talking about. But Mr. Gunn is to be commended for straddling that fence between full-bore horror and silly-spoof satire, and the result is a tongue-in-cheek, brains-on-wall, splatter-happy fun-fest that should thrill all the old-school horror fans out there. When you hear the phrase “horror-comedy,” your first thought might be of Scary Movie, if you’re young, or Student Bodies, if you’re old. But there is a distinct sub-genre of horror flicks that aim to balance William Castle-style creepiness with a self-aware sense of snark, and Slither manages to deliver cheery chuckles and bloody bedlam in equal measure.

But the ride doesn’t come without a few speed bumps: The flick’s opening act really begins to wear out its welcome by the 20-some minute mark, and time that should be spent fleshing out the colorful characters is, instead, spent focusing on a husband-wife relationship that isn’t nearly as thrilling as Gunn seems to think it is. There’s also a healthy dose of editorial confusion that runs throughout Slither; as the action heats up, several scenes just sort of interrupt the one before it, instead of there being a fluid flow from chaos to carnage. One suspects there may have been a few late chops in the editing booth: a female side-character pops up with a plump-looking baby attached to her hip, yet after Mama gets all Slither-ized, there’s no other mention of the now-helpless tot. (Not that I necessarily NEED to see a baby being eaten by a slime-soaked snot-creature, but c’mon, Gunn showed us the baby for a reason, right?)

And this is just a very minor nitpick, but Gunn might have been better served by doling out his dispatches at a more leisurely pace; most of the background characters make their icky exits during one extended scene, which leaves the viewer to hang out only with the “hero gang” of characters you pretty much know are going to make it to the end credits … or will they?

And while it's true that the flick really does take its time getting started (which is bad), Slither boasts more than enough assets to make the trip worthwhile (which is good). Aside from Gunn's sly, silly, sarcastic screenplay and two truckloads of adorably gory gristle, we're also treated to a game cast of actors who know precisely what kind of movie they're in. Gregg Henry (as the cowardly mayor), Elizabeth Banks (as a devoted damsel) and Michael Rooker (as the doomed Grant Grant) deliver fine supporting work, but leading man Nathan Fillion provides a spine for Slither. His Chief Pardy is equal parts heroic, clueless, honorable, and lazy, and Fillion manages to create a character you’ll actively like after only about four minutes of screen-time. Known mainly as the conflicted anti-hero of Firefly / Serenity, Fillion has the wit, the attitude, and the scruffy charm of a young Harrison Ford -- only funnier.

Special note of appreciation is due to the approach taken on the special effects front. Gunn employs CGI trickery in some of his larger “glory shots,” but whenever we’re up close and personal with the horrific beasties, it’s nothing but paint, latex, and wonderfully goopy gore. Put simply, there’s nothing like “practical” splatter, and the best monster moments of Slither recall, heck I’ll say it, Rob Bottin’s legendary work in Carpenter’s The Thing. Kudos also to Tyler Bates’ jaunty, pulpy score and to Greg Middleton’s slick, slimy cinematography.

Basically, Slither is a love letter to all the goofball horror flicks that aim to give you a few shivers while keeping a few chuckles tucked up its gore-drenched sleeve. If you're the type who appreciates the half-scary, half-silly comic book-y approach of titles like Gremlins, Tremors, and Eight Legged Freaks, I'd bet you $9.50 and a small popcorn that you'll enjoy Slither.