BATTLEFIELD EARTH (PG-13, 117 minutes)

Teens likely will be unable to stay awake, let alone make any sense out of this flat-footed sci-fi epic. Boring, murky and full of unintentionally funny lines, this pet project of star John Travolta is based on the 1982 novel by L. Ron Hubbard, founder of the Church of Scientology, to which Travolta belongs. The violence makes it iffy for preteens, although most of the killings take place off-camera. Little blood flows amid the gunplay, bone-crunching fights and slow-motion, glass-shattering stunts. Still, the deaths of humans, horses and cattle are strongly implied. Phobics, take note that rats are used as food. Other elements include mild profanity and comic sexual innuendo. It's the year 3000, and mankind is an endangered species, conquered by a giant, longhaired race of space aliens called Psychlos. Yet rebellion's afoot in the form of gutsy Jonnie Goodboy Tyler (Barry Pepper). Captured by Terl (Travolta), the aliens' duplicitous chief of security, Jonnie submits to enslavement in order to learn their language and ultimately lead the revolt. In days, he and his comrades evolve from cave dwellers into fighter pilots. Full of holes and mighty cheesy is "Battlefield Earth."