In more detail, within the setting for each film you can play as the humans or as the Predators. As the humans, you play the co-op version of the game as in Legendary Encounters: Alien, recruiting, scanning and attacking the same way while trying to achieve objectives. When you play as the Predators, the game is player vs. player instead of co-op, with each player assuming the role of a Predator hunting for the most honor (VPs).
Legendary Encounters: A Predator Deck Building Game is a standalone game in the Legendary Encounters series that is fully compatible with Legendary Encounters: An Alien Deck Building Game. Specifically, you can use the Predator deck in Alien or the Alien deck in Predator. Similarly, Predator is also compatible with the Marvel superheroes version of Legendary but cannot be fully integrated.