It's a first person shooter with RPG elements. You level up and develop your character to specialize in something (for example, you can make your Siren have elemental perks or heal team members or whatever). You have to pick up new higher level guns to keep up with the enemies, which are usually psychos, midgets, bandits, or just alien monsters. It's all about finding loot on this wasteland of a planet (the second game has more environments). You can play with up to 4 people, and that's where the real fun is. It's great. :D