Players of the Wii U game—which allows you to make and share your own Mario levels—can now add keys and locked doors to their designs. Additionally, they can drop in Red Coins. Collect five and a key appears.

It’s a small feature addition, the sort of thing that wouldn’t take Nintendo very long to implement. But it will cause a fundamental shift in the types of levels players can create. With keys, doors, and collectible-triggered unlocks, you can make non-linear levels that demand thorough exploration to finish. This can lead to levels that feel more like an adventure than a run to the finish.

One extra feature that goes along with the key item adds another wrinkle. Keys also can be hidden inside enemies, which must be defeated to get the key. This unlocks the ability to create boss fights—those epic enemy encounters that must be won before Mario can move on.

Since the game’s September launch, Mario Maker creators have pushed against the limits of the game’s editor, which is intuitive and seamless but doesn’t quite let you do everything you’d find in an official Mario level. People have devised elaborate kludges to simulate mid-level checkpoints and have tried creating “boss battle” type situations to varying, and ultimately unsatisfying, results.