When coming up with the framework for the game I wanted to make, I might have bitten off more then I can chew. As a result it sometimes takes me years to go from the realization of a design problem, to discovering a solution, to actually implementing it.  
When building my levels, treasure chests are the main reward for exploration. But what I found quickly is that if I fill my world with treasure chests, the feeling of finding one dulls quickly. In general, I'm implementing a clean, tilebased aesthetic, which is perfect for eyes to scan quickly. Anything you see becomes the objective immediately, which then turns exploration into a list of chores to go through before you can move on. In other words: if you can see it, you will not miss it.  
I eventually found a very fun solution in Kirby and the Forgotten Land, but it wasn't until now that I actually got to sit down and implement it.  
A feature like this makes it so the players can actually miss secrets and go about their business without even realizing. Those who aren't thorough might overlook things until way later and that is precisely the kind of experience I want to shape.

It took me a while to solce this one problem for my level design