According to Dev from KidOYO, "Code Caching is an exploratory social game or exercise in storing and accessing stored resources, both in digital or physical worlds. Similar to "geocaching", kidOYO Code Cache allows you to discover hidden features of information, learn new things, and even create your own code cache for others to play with! There is no limit to the creativity that may be used in designing a code cache, and stored resources can take any format that may be discoverable by others in an interactive manner."
think of it as some sort of a set of puzzles. Each web page is a level and each level has a secret code you need to figure out to advance. This code cache has 64 levels!