Just comparing something like Godot to a blank text file. Godot has prebuilt math and data structures in it....so me writing out the math functions and data structures for my blank text file ahead of the competition is okay...? Effectively the coded outline for the game can be done ahead of the 3 hours...? What's the consideration here? Any generic game object's outline can be prewritten...? Or no, and its up to me to choose someone else's engine and tools that excel at making the desired game quickly?

Of course, you can build on your work! The goal is to practice game development and improve your skills, become more efficient! :)

ok, I guess I'll just think of it as starting with a blank doc to make a newgame, but i can grab code or whatever from my other projects as desired along the way