4. Mass Effect
What do you get when you mash the space opera of Star Wars with the political machinations and social commentary of Star Trek? You get Mass Effect, a sprawling, complex, and beautifully-realized sci-fi world with a great story that emphasized the player's choice. From the beginning, you are allowed to create Shepard's backstory, ethnicity, gender, and facial structure. Throughout, you can choose how to act towards various people and situations, crafting your own narrative.
This emphasis of player choice has permeated the medium since 2007. RPGs are defined by their abilities to offer the player profound choice with lasting in-game consequences. The Walking Dead, from Telltale Games, won acclaim from critics and fans for its focus of choice-based storytelling. Moral systems became a common feature for the next few years, usually in the case of binary good/evil forms. All thanks to Mass Effect.
