There is a decent amount of gore in this film. The killings are well orchestrated, however in the special effects department this film is really lacking.
The film is dull in the beginning. The impregnation sequence leaves a lot to be desired. Just compare how in Alien directed by Ridley Scott, the "face-hugger" sequence is well shot and we see the creature clearly attached to the face of its victim and also as the creature bursts out of the chest.
Here the alien creature transfers its genetic material through a clear plastic or glass tube inserted into the vagina of the victim. A sort of artificial insemination. And this is the topic film pokes fun of.
Full Plot: On a desolate planet, a team of 12 Xeno project scientists are conducting an archaeological excavation to locate remnants of an ancient civilisation. Soon after an underground tomb network is found to contain crystals and wall inscriptions, photographer Dean White (Dominic Jephcott) is engulfed in a sudden rock blast and left incapacitated. Deciphering the alien language in the caves, xenolinguist Mitch (Trevor Thomas) suggests that the civilisation based itself on dualism: the planet orbits a binary star, and a pair of twins appears to have ruled the race that once inhabited it. Medical assistant Sharon (Heather Wright) announces that an energy field surrounds the crystals and proposes that a "chemical intelligence" ordered life on the planet.
A crazed Ricky Williams (David Baxt) is compelled to re-enter the caves when a sample of crystals starts to pulsate and the chemical intelligence exerts its influence through a mark on his arm. Thrown into a grille in a compromised environmental suit, a panicked Gail (Rosalind Lloyd) commits suicide, removing her helmet and freezing to death in the inhospitable atmosphere while attempting to amputate her trapped foot with a chainsaw. Documentation officer Kate Frost (Stephanie Beacham) shoots Ricky with a harpoon gun just as he is about to open both the inner and outer airlock doors and render the air inside the base unbreathable.
After the burial of Ricky and Gail, Mitch and Sandy (Judy Geeson) return to the caves to gather more crystals. A monstrous creature appears and dismembers Mitch before proceeding to rape Sandy. Found distraught, she receives treatment from Sharon and the chief medical officer, Karl (Barry Houghton), who determines that the assault has initiated an accelerated pregnancy in defiance of the regular intravenous injections of contraceptives provided to the women in the team. When further explosions in the tomb network scupper chances of deeper investigation, the surviving members of the team await the arrival of a Xeno rescue shuttle.
The intelligence assumes control of Sandy through a similar mark on the arm. Unhinged, she demonstrates superhuman strength while murdering Barbra (Victoria Tennant). She then proceeds to mutilate Dean and the remains of Mitch, drinking their blood. The rest of the team seek refuge in the Operations Room as Sandy obliterates important hardware-'including the base transmitter-'with explosive charges. When the imbalance in her mind appears to correct itself, Karl, Sharon and Commander Holly McKay (Jennifer Ashley) attempt sedation to spare her unborn offspring. However, Sandy returns to an aggressive state. Holly and Karl are killed in an accident with heat-sealing apparatus, whereupon Sandy disembowels the corpses.
Senior officer Mark (Robin Clarke) contacts Sandy, who is his romantic interest, from the Operations Room to stall for time as Kate and operations chief Gary (Stephen Grives) leave to commandeer chainsaws. The ruse uncovered, Sandy harpoons Gary outside the airlock, breathing the toxic atmosphere to no ill effect as she mauls his flesh. Preparing for a final confrontation, Mark stumbles across Sandy's newborn mutant twins. He entrusts them to Sharon as their mother blasts through the Operations Room door and smashes all the equipment inside, although she has lost her unnatural strength. Crippled from the blast of an explosive charge, Kate is gored to death. In a last stand, Mark strangles and kills his former lover with a ripped-out cable. He returns to Sharon to find one of the twins biting at her gashed neck, before its sibling launches itself at him.
One month later, Xeno Auxiliary Module 047 lands on the planet to investigate the loss of contact with the team. With the base in ruins, the mission records lost and the complement of scientists either murdered or missing, combat marksmen Corin (Kevin O'Shea) and Roy (Robert Pugh) abandon the search for survivors and pilot Jeff (John Segal) radios Xeno control for clearance to return. The final shots reveal that Sandy's children have concealed themselves in a storage compartment onboard the shuttle.
Conclusion: rent it(and watch once) and DON'T BUY it. Bottom line: I've seen better films than this (The Thing 1982 and The Fly 1986 for example).
Review by Vivekmaru45 from the Internet Movie Database.