
To start, Dues Ex Human Revolution is set in 2027 Detroit and it is a prequel to the original Dues Ex game which was released in 2000. People are becoming augmented which essentially means that their enhancing themselves with new technology hence the title "Human Revolution".
There are tensions between the Purists (who are against augs) and the large corporations (who are pro-Aug Sarif, Tai young etc). Both of them will have to face each other eventually and you're the only who can desire both their fates.
You are Adam Jensen, an ex swat member who has been heavily augmented due to a tragic accident at the start of the game.
He is an interesting character overall...