I was able to finish the game a couple times and unlock the secret file. I'm a bit confused by what was in there though. Are you sure you've but the right thing?
Hello Side B! Wow, congratulations, amazing!
Did really not expect anyone trying to solve this so fast! ^^
One can try to look deeper into it - theoretically, what's there could lead to more.
But then again, that 'more part' isn't really all there yet, so... maybe a bit later, haha.
But man, thank you for checking out / testing the game!