Let's kick things off with one of the ballsiest release strategies for one of the greatest video games of all time.
Before they unleashed legendary puzzle-platformer Portal upon the world, it's fair to assume that Valve must've known they had something truly special on their hands, right?
Yet that wasn't quite the case. Valve had little idea how their physics-based platformer would fare with players, and so made the decision to release it as part of 2007's The Orange Box - a compilation also containing Half-Life 2, its two episodic follow-ups, and Team Fortress 2.
Portal had little hype from Valve pre-release and nothing in the way of a lavish marketing rollout - it was simply an extra puzzle game bundled into a compendium containing a host of known quantities.
Valve also deliberately kept Portal's length to just a few short hours in case it failed to connect with players at large.
But of course, it wasn't merely a success - Portal was often singled out as a hugely pleasant surprise and even the very best game in the entire Orange Box.
Even with Valve themselves doubting its potential, Portal went on to win numerous Game of the Year awards and, of course, led to development of a sequel which arguably managed to surpass it. Not bad for a pack-in game nobody knew anything about.