Steps of how to set it up:
Step 1. Set Asriel's head's layer to layer 3-5 and Asriel's body's layer to layer 1-2 in the appearance option.
Step 2. Make sure gravity is unchecked, if it's checked, then uncheck it, or else the game will NOT work very well.
Step 3. Set both the main and secondary background colors to a random color.
(Optional) Set the background's type to rain.
Step 4. Insert ANY attacks you want to add in. ;)