Eduardo (Blair Witch Project) Sanchez directs an SF/horror film the old-fashioned way: with an improbable plot, hand-made gore effects, and a generous measure of suspense and shocks. Altered's mood varies from thrill-ride fun to grim, from wide-eyed panic to action-heroic--with welcome doses of humor and good-ol'-boys(-n-girl) characters that are surprisingly non-annoying; the script knows they're rednecks, but doesn't laugh at them.
If you can stand the gore and enjoy horror comics and The X-Files, this one is comfort food. And it's the kind of direct-to-video title Instant Play was made for; one can only hope that Altered inspires more would-be grindhouse auteurs.
I'm sorry to note that I wanted to recommend another low-budget horror gem, Splinter, but it's off the Instant Play--although you can rent the disc. Please, Netflix, extend those licenses!