is the retribution tab part of it? 

It's a "Fantasy role-playing game with real-time combat, persistence, complex NPCs, extensive character customization, local multiplayer with PVP, and a story about foiling a conspiracy that threatens a colonial, developing world."

Story isn't added yet, everything else - kind of.

Hit ESC anywhere in the game and click "Toggle player 2"

You might also want to customize controls after that. I think best way to play is if player 1 uses keyboard and mouse, and player 2 uses a controller. Or two controllers.

...Basically experiment and find what works best for you.