10 Most Important Video Games Ever Made

2. Team Fortress 2

Team fortress 2, despite its exorbitant production time (which lead many people to coin the term 'Valve time') is considered the premier in hat-wearing simulation. With advanced physics such as hats falling off the players character when hit with sufficient force, it really pushed the boundary of existing hat simulators, which only allowed a narrow view of the world such as appearance.

Updates to Team fortress 2 also turned the game into an economic experiment, allowing users to craft and purchase virtual hats and trade these hats among themselves. Later updates added new hats, and 'miscellaneous' items, allowing players to further customise their appearance beyond the realm of hats. The emergence of an in-depth economy, based primarily around hats and the components needed to craft them, has turned out to be a reliable source of income for Valve software.

Team Fortress 2 has pioneered in the realm of in-game economies, and while met with some criticism that such features detract from central game play aspects, is undoubtedly an important game to consider, particularly in the area of hats.