Aliens has this crude dialogue on this species:
Frost: “Hey, I sure wouldn't mind getting some more of that Arcturian poontang, remember that time?"
Spunkmeyer: "Yeah, Frost, but the one that you had was male."
Frost: "It doesn't matter when it's Arcturian, baby.”
Wikia has this:
The Arcturians are a humanoid, mammal-like ...
The predator is there as a clean up man. His killings leave no trace evidence that the humans can make use of. The alien victims though could have traces of alien DNA and the predators do not want humans getting a hold of that.
Isolation has no continuity with the prequels as far as I can remember. My advice to you is this:
Watch Alien, the theatrical cut.
Play Alien: Isolation.
Read Alien: Out of the Shadows, set after Isolation but before Aliens.
Read Alien: River of Pain, set after Out of the Shadows and acts as a direct precursor to Aliens.
Watch Aliens, the director's cut.
Well it honestly depends on what you consider canon, in a manner of speaking. The video game has, I think, been considered tentatively canon, as another user pointed out. It's never been referenced in the movies (because of course it didn't exist when the movies came out or has taken place long after the two Prometheus movies), so if you go solely by those, ...
The first two movies should be enough. I can't think of anything in the game that isn't covered by them. Come to think of it, only the first movie would be required. You just need to roughly understand what happened to Ripley and co. and that corporations in the future are not nice people.