I started working on the Vinland Game on Jan 20, 2017, and I last updated it on Dec 20, 2018.
By that point, I had basically completed 80% of the game, but Blender Game Engine was going to be discontinued and I didn't want to work on an unsupported engine.
Transferring to Godot would be possible, because many of the coding concepts are similar. Python and GD script are not very different. However, Blender's method of dealing with objects is quite different, and all the built in methods are different, so things like animations, particles, movement etc... would all need to be different.
I've been making games for several years, so I picked up a lot of transferable knowledge before I started working on the TBT game. It was something I approached several times during that period, but I didn't have the skills to complete.
Making a full game is difficult and requires a lot of specialist knowledge and experience of project design and planning.
You can get an idea of the size of the project by checking out the github repo (code only) https://github.com/Pickledtezcat/vinland_2018_1942
Feel free to dig around in the code. It's not beautiful because Blender Game Engine was basically an empty canvas. Things like image editing, terrain placement, state machines, UI, AI and so on all had to be built from scratch. it's nice working with GODOT where a lot of those functions are already coded and available.
My new project on GODOT is different. It's a Roguelike Puzzle and building game, though it reuses some code from my earlier project; since they are both grid based games.