it's hard to describe deus ex without having you just play it but it's like part FPS, part RPG and part Adventure game. You can progress through the game in whichever manner you please and there's a ton of character interaction. You can go through guns a-blazing and just kill everyone to reach your goal or you can choose to not kill anyone at all and talk and sneak your way through situations
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http://i.imgur.com/FczF1.jpg
http://www.yourgamercards.net/trophy/a/CaptainRockman.png