One of the older games in my collection is Intruder, a cheap pocket game that was published in 1980. Aside from a few typos in the rules and even on the CRT, Intruder is an excellent unlicensed simulation of Alien. The default scenario is co-op, but there are also rules for a player-controlled xenomorph. There is also a scenario that replaces the regular crew with space marines, which is amazing because the movie Aliens is based on the same idea but came out six years later.
Intruder incorporates as many elements as possible from Alien, except that it lacks the traitor element. Instead of having players collecting scrap, the engineer characters can go to a workshop type room and spend a turn or two making either electric prods or flamethrowers. The xenomorph has a chance of growing each turn, and each new life stage includes a new power that isn't determined until the next encounter with the creature. The crew isn't allowed to kill the xeno during the first two life stages, and the medical personnel are never allowed to kill it. You can try to airlock the creature, though 2 of the 11 powers prevent that. There is a space shuttle for escape, and there is a self-destruct sequence that can be activated. The xeno is concealed by facedown tokens that can also represent escaped lab animals (like Jones the cat) or false readings on the motion detectors.
Thanks to Kickstarter, Intruder got a very fancy upgraded edition in 2013, as you can see in this Youtube video: