The Key Barrier is a gimmick from the Make a Good Mega Man Level series. It is a wall that must be unlocked with a Key.
Key Barriers were first made available in the devkit for Make a Good Mega Man Level 2, where they appeared in 10 entries, as well as the Wily stages Classic Castle, Inner Sanctum, Unobtainium Mine, and Reality Core, the Tier X stages Hardcore Parkour, Wily Fortress VR, Deep Thoughts, Swiss Hotel, and Null and Void, and the Pit of Pits sub-level "Water Test". They also appeared in the Stage 1 Make a Good Mega Man Level 3 Judge Application Level Gate 303, and the Stage 2 MaGMML3 judge application level Proxima Station. Make a Good Mega Man Level: Episode Zero used them in 12 levels, most prominently in Offshore Hangar Cluster.
Key Barriers serve as solid objects. If Mega Man collects a Key in the level, he can use it to unlock a Key Barrier, making it disappear. Mega Man can obtain a Key either by picking up a single key or by picking up a certain amount of Key Coins (the amount required depends).
- The design and functionality of Key Barriers are based on the locked doors from Zelda II: The Adventure of Link.
- In MaGMML2, the sprites for Keys and Key Coins were taken from Super Mario Maker, where they serve as sprites for the game's Key and Key Coin objects when the style of the level is set to Super Mario Bros. 3. Starting with the Megamix Engine, Keys and Key Coins use custom sprites instead.
- The sound effect used when a Key Barrier is unlocked is the same as when a Wheel Cutter is released.