Valve

For promoting free-to-play and indie games while simultaneously crafting a string of massively profitable hits. Last April, prior to the much hyped release of Portal 2, the developer initiated an addictively complex viral marketing campaign for the game, enticing players to engage with a bundle of 13 underrated indie titles by embedding a series of hidden clues in them. It was a win-win for the indies and Valve. Portal 2 sales topped 3 million just two months after its launch.