A side quest is an optional adventure or diversion undertaken by an individual, typically outside the realm of ones primary goals or responsibilities. In video games, a side quest is any part of the game that is not required to complete it, and completing them generally brings rewards such as money or items that are otherwise unavailable, or unlocks another side quest. Some side quests may provide challenges more difficult than any content available through the main storyline, allowing more casual players to still complete the game and see the plot resolved, while also giving gamers seeking an additional challenge something to go after.

SideQuest is also the name of a desktop app for Mac/Windows/Linux that allows users to browse and install content on their Oculus Quest via sideloading.