In Snap! 10, which is in development, there are blocks that can control the Snap! user interface with more possibilities than what the default primitive blocks can do. What I am speaking about is found in the Microworlds library. So I come up with an idea, to make a horror game that interacts with the UI to try and frighten the player. Why not collab and contribute to one project?
As I don't want unstable extensions to break the project while it is being developed due to unexpected changes, let's brainstorm (write some scripts and concepts, don't share projects) and after Snap! arrives, start with the prototype and be exempt from the rule. Also, the current Snap! version doesn't support loading extensions from future versions.
Beware: Try not to misclick on the block called "show loading screen", as this will lock the interface in a black screen with the words "loading" until the "hide loading screen" block is run, which will make you lose your work if you don't have the other block usable and didn't save.
Basically, in Snap! microworlds are restricted programming enviroments that can disable parts of UI, such as the sprite corral, green flag button, etc.. and even can trigger actions by itself, such as automatically focus on coding on one sprite, all without JavaScript.