This project doesn't work on TurboWarp To enter detector mode wait until the end or stop the project, and click and hold the stage for 1 second. Then it will detect when the first sprite is changed. I got the idea of using an object as list here: https://scratch.mit.edu/projects/1068153464/ If an object has the "length" property set to a positive number then Scratch can use it almost like if it was a list. Some blocks don't work though - real lists (arrays) have built-in methods that these blocks use, but JavaScript methods can't be defined in the JSON for safety reasons. I tried out if the default input in custom blocks can be set to an object (through JSON editing) and it works. However if the object is in a list or variable the project won't save and if you download it that file can't be opened. I also tried out if the custom block generates the same or different objects every time and I found that it almost always returns a reference to the same object except when the editor opens the sprite or code is changed.
