Ok, first things first: what's an ARG? The acronym stands for 'Alternate Reality Game', which basically means it's a game that's dressed up as... something else. ARGs usually run across different forms of media to act as viral marketing for... yeah, something else. They work by blurring the line between fact and fiction, reality and game world, which usually means people talk about them outside of their target audiences. They bleed into reality.
Being at the cutting edge of technology, video games often use ARGs to feed secrets to the community or tease new releases. Not only do they give fans something to chat about, they aim to blur the lines between game and reality, to make people think about the franchise beyond regular previews, reviews and news stories. That's the theory, anyway. Here are 6 genuinely smart ARGs that have been used to promote your favourite games.