Stalk the depths of the Nostromo as an Alien or brave its halls as Ripley and the crew in ALIEN. In phase 1, the aliens infiltrate the Nostromo and prey on its crew. Meanwhile, the crew uses motion detectors to track the aliens' whereabouts as they set the Nostromo's self destruct.
The quicker the auto destruct is set, the easier the second phase will be for the humans.
In phase 2, the board flips over, and the crew sprints through alien-infested corridors to the escape shuttle. If they don't escape in 10 minutes or less, they won't need a rocket to fly through space!