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If you play this game, all that comes up is "Theres nothing here..." (And thats all there is- look at the code). But then, how is there a custom cover image?
It's simple: You don't have to update your cover image (w/ F7) with your code.
Just comment all/most your code, make a cover sprite, show it, press F7, uncomment code, remove the sprite showing up, and boom. You easily have made a cover image that isn't accessible from the game itself. I'm probably not the first person to find this out, but it does work and I found it on my own, so I'm writing this.
EDIT: To remove the console, put the sprite drawing into a _DRAW() loop, that should work better.