There were a lot of Civilization fans who were disappointed when the latest entry to Civ's legendary empire-builder came out. It looked great and introduced new hex-based mechanics that made war a far more strategic affair, but it just lacked the depth that made Civ IV one of the great strategy games of all time. The Gods and Kings DLC for Civ V went some way to amending that, though there was a feeling that it was just bringing the game up to the level of its predecessor rather than surpassing it. When Brave New World came along though, it finally propelled Civ V to greatness, adding a whole bunch of new civilisations to play as, but most importantly tweaking the mechanics in ways that made a huge difference to the gameplay. Trade became a mechanic that players had direct control over, and establishing trade routes key to making money, rather than just building near tiles with the Gold resource. Crucially, the late-game was completely overhauled with the introduction of tourism and ideologies, which diversified the phase of the game where before it tended to slow down. This is a prime example of great strategy game DLC, refining the mechanics of something brilliant but flawed to help it unleash its true potential. You can argue that Civ V should've been like this all along, but the new direction for the series was clearly a learning curve for the developers, and this DLC proved that they put in the effort to perfect it.