I have previously toyed with Unreal Engine, Unity, and Godot. I had the most success with Unreal, however I wanted to know intimately how the code worked. Beyond that, this project will ultimately help with my programming career to understand lower level programming.
The decision to ultimately abandon existing game engines, and reinvent the wheel for the nth time, came from the design philosophy of You Have to Win the Game. I can’t find a video of the credits anywhere online, looks like I’ll have to record it myself.
Beyond that, I’ve been following a plethora of resources to get my started.
https://www.youtube.com/user/TheChernoProject
https://www.youtube.com/c/RandallThomas
https://www.youtube.com/c/AxelWard
https://learnopengl.com/
And many, many books on C++, OpenGL, Game Design, etc.