1. Which challenge didn't work exactly?
2. The candy you earn gets more valuable the further you're able to run.
3. The current demo is just a stripped down version of the game, so there is no way it could interfere with that. If you played an older version, it may help if you delete your old savefile too. You can find it here: C:\Users\User\AppData\Roaming\Godot\app_userdata\Eternal Escape