Some of our favorite gaming memories involve hours and hours of investigating a level's many nooks and crannies, only to stumble upon an extra, secret level to explore.
In this list, we've collected some of our favorite secret levels of all time, based on the quantity and quality of the hidden content.
Here are the top 10 secret levels in games.
Mile High Club is the perfect exclamation point on the end of Call of Duty 4’s fantastic campaign. The brutally hard bonus mission unlocks after players complete the story, and drops players into a frantic firefight to clear out a double-decker airplane. It only lasts an insane 60 seconds on Veteran, requiring near-perfection to rescue the VIP and unlock that coveted Mile High Club achievement.