So, you played through Aliens: Isolation, and you can't get enough of those friendly xenos?! If that's the case, then maybe Aliens vs. Predator Classic 2000 is going to be of interest. The good news is thus; GOG.com is giving away the classic title for free. It's a suspenseful sci-fi first-person shooter with three different single-player campaigns, one for each species, and a multiplayer mode to round things off. All you have to do to get the game is sign up for the Galaxy Beta and then help improve the performance of the multiplayer component of their incoming platform. All the information you need can be found here.