Genuine exploration and discovery is one of the key things that distinguishes video games from other mediums. Player actions are able to directly affect how the content is enjoyed, offering a non-linear experience compared to something like a movie. While the joy of exploring an environment and completing challenges outside the main campaign can often be a reward in itself, developers will frequently include motivation for doing so. The Xbox 360 console popularised the idea of rewarding players with achievements, in exchange for completing particularly difficult challenges or uncovering hidden locations. It can be addictive to collect trophies or achievements, but sometimes a more solid reward can provide even greater motivation. Among the most rewarding unlockables include secret characters. These characters can allow you to experience a single-player campaign in a totally different way (with new abilities or movement options,) or even give new ways for you and your friends to battle one another. This list takes a look at ten of the greatest unlockable characters in gaming history. From legendary hidden fighters, to bizarre characters that youd never expect to see in their respective titles, each of these entries will give you more than enough reason to replay many of your favourite games.