The InFamous series from Sucker Punch consists of massive open world environments that the player explores through  narrative/character interactions, missions and story progression points. The player is free to explore the environment at will, however the player can only progress or "unlock" areas if missions are completed or other goals are achieved. These missions are discovered by interaction and exploration of the game spaces so the environment design must invite and motivate players into the world unconsciously with visual storytelling, lighting, detail and animation, just to name a few tactics.