The problem with the "Alien vs. Predator" series is that the humans keep getting in the way.

"Aliens vs. Predator: Requiem" is the second movie ripped off from the bestselling video game, which in turn was ripped off from separate Reagan-era monster-movie franchises. That's not necessarily a bad thing; an effective B-movie doesn't have to be original, just well-crafted. "AVP: Alien vs. Predator" (2004), for instance, was proficient sci-fi/action snack food, nothing more or less. "Requiem," by comparison, is a plate of nachos left in the microwave too long.

The problems with the movie are twofold and easy to spot: The acting stinks and you can't understand what's going on. Set in picturesque Crested Butte, Colo., the film kicks off with a Predator spaceship crash-landing on Earth with a cargo of Alien lab specimens. As the critters fan out into the Colorado forest and begin their face-hugging, chest-cavity-incubating ways, a dreadlocked Predator blasts off from his home planet to clean up the mess.

Your inner fan-boy might be interested; mine was. Shane Salerno's screenplay, unfortunately, plunks us down with a bunch of locals out of the U.S. government's Daytime Soap Relocation program. Prodigal bad boy Dallas (Steven Pasquale of TV's "Rescue Me"), his lovelorn kid brother (Johnny Lewis), the lissome blonde he pines for (Kristen Hager), the beleaguered town sheriff (John Ortiz) -- these are screenplay-software templates, not characters. A tough-mama Iraq War vet (Reiko Aylesworth), on the other hand, brings back fond memories of Jenette Goldstein's Private Vasquez in 1986's "Aliens."

"Requiem" spends far too much time with these stick figures and not enough with the creatures, who lack motivation but are fun to watch. Or they would be, if directors Colin and Greg Strause used more than two foot-candles to light the film. Either for budgetary reasons -- i.e., to hide the zippers on the rubber suits -- or for purposes of mood, "Aliens vs. Predator" has been underlit to the point of incomprehensibility. Factor in hectic editing and a bombastic score, and you have an endurance test, not a movie.

As the town population gets thinned and the gore factor goes up, the Predator goes thingo-a-thingo with various Aliens, including what looks like a crossbreed PredAlien. Where he (she? it?) came from isn't very clear, although it might have something to do with a mysterious syringe that gets injected into somebody at some point. The Predator also carries a vial of glowing blue liquid that dissolves whatever it touches. I found myself craving a bottle of the stuff and devoutly wishing it were retroactive.