Hi! Yes I didn't have any experience making 3D games before to be honest. I followed the tutorials here:
The basics are from a youtuber named Miziziziz:
How to make a Doom clone in Godot in 13 minutes - YouTube
How to make Wolfenstein 3D style levels in Godot - YouTube
For the pixelated effect I used a tutorial by TheBuffED:
How to Create a Simple 3D Pixelated Effect in Godot without Shaders - YouTube
Using these tutorials and others found on google, I was able to complete it before the time was up!