The company Valve manage the Steam IP, easily the biggest software distribution platform for PC users. The company wanted to increase the engagement of its users (thats us) and keep us playing for longer and buying more titles. How do you make people play games even more? By introducing rewards! The Steam Trading Card initiative was launched to let you win cards for games youve bought, but you also have to trade cards with other players to try and collect a full set. This taps into gamers latent desire for collection and completion. Steam further appeals thanks to the rewards on offer for completing a full set avatars, backgrounds and discounts.