http://www.fiveminutes.gs/
Five Minutes: A brief, cinematic game taking place during a zombie apocalypse.
What I enjoy about it is the story is told through clips, so you have to guess at what is happening to some degree, and the interaction within allows for additional elements that help immerse you into the experience.
http://store.steampowered.com/app/239030/
Papers, Please: A pixel-style, choice-based game.
The simple style and relatively neutral color pallet create a wonderful atmosphere, and the dialogue and story create a very harsh and sadly realistic world.