Alien: Isolation was, in my opinion, pretty crap. Crew Expendable however is fantastic. Now I know you'll be thinking they're pretty similar but there are a few key differences that make them very different beasts. You may in fact say that, compared Isolation, Crew Expendable is an - ahem - alien experience...
Anywho, Crew Expendable allows you to play as a few of the crew members on the Nostromo as you try and seal hatches to blast the Alien into space. You've all seen the film, you know what I'm on about. Featuring more mind blowing fan service in the form of incredible renderings of the characters and returning voice actors the scene is perfectly set.
The main reason it's better than Isolation is its short and intense. You have to shut the hatches and try and get rid of the Alien. You're armed with a flame thrower and can collect other items but all the while you know your entire purpose on this mission and all the while you know you have to outwit the Alien. You can blast through and scare the beast off with flame or sneak around it, either way the tension remains high as the weight of your mission bears down on you. If you're playing the game then odds are these are characters you really care about, you know them inside and out and want to save them.
The relative brevity of the game, alongside the attachment to the characters and the sense of purpose and lack of repetition in the mission design make this utterly thrilling. It's not perfect, the voice acting does sound somewhat dialled in and the older sounding voices coming out of the young faces is frankly terrifying but from a gameplay perspective it does everything that Isolation should have done.
It isn't worth buying Isolation for but, if you already have Isolation, then I implore you to try this out, you will not be disappointed. This is DLC done right.