Alien: the Fan-Made Audio Drama
Found this on YouTube and finished listening to it today. It's not bad, has lots of its own unique touches including Ripley being male. Lots of music and sound effects to help you feel immersed.
https://www.youtube.com/watch?v=OlQRuz-_DEk
I still would like to see the original Alien script by Dan O'Bannon (the one with the pyramids and no android, etc) made into an audio drama so it can finally be realised, somewhat.