Did you use something like Unreal or Unity for this, or start at a more foundational level and deal directly with graphics APIs etc.?
I ask as a matter of curiosity and personal interest--it's something I'd like to learn as a hobbyist, but my knowledge is limited to simple OpenGL tutorials and the (relatively speaking) watered-down Graphics course I took in College years back.
I would strongly recommend starting with an engine like Unity. You can prototype and get something functional SO fast. It's extremely rewarding and keeps in the dopamine loop. There's not sense in struggling through OpenGL to build an engine from scratch unless that's what gets your rocks off or you have an explicit need for it.
I worked in WebGL without a game or graphics engine sitting on top, because I'm both a masochist and egoist. If you haven't ever dipped your feet into RTR before (or don't have an interest in "doing everything yourself" / flexing or have a desire to be productive without building your own tooling), I have to recommend Unity or Unreal.
