Prototype Casino

 

Prototype may be a bit old by today's standards, but it is one of the most unique open-world games ever made. Alex Mercer, the protagonist, is literally the most powerful living creature on the planet. 

He can shapeshift into a monster or disguise himself as another person.

If the players feel too overpowered from using the superpowers, they can transform into a soldier and roleplay instead. Players cannot drive vehicles, but they can glide across the city.