In-game collectibles have become a mainstay of modern gaming. Almost every title that comes out features a variety of optional hidden items littering the world players have to seek out. While they are rarely an essential part of the story, they can add extra enjoyment to the overall experience if done right.
The very best collectibles are expertly hidden to encourage exploration and come along with a system designed to help the player keep track of what they still need to find. They also tend to provide some tangible benefit, whether it be extra powers, additional lore, or ridiculous cheat codes. It's no coincidence many of the most addictive video games ever contain a slew of fun goodies to search out.