Lego City: Undercover is an Action-Adventure, Sandbox, Open World and Single-player video game developed by TT Fusion and published by Nintendo. The game takes place in the massive Lego City and lets the player assume the role of the protagonist, who is an undercover police officer named Chase McCain.. While it is not true "open world" like Lego City, the settings are expansive and non-linear. Different paths are made available at all points, and, once and area is complete, it begins to open up more places to go. I have Lego City Undercover, Lego Worlds, Lego Batman 3, Lego Avengers, and others, and I will say, thus far, this is my favorite..