Unfortunately, making 3D engines takes time and I don't like them as much as I used to. The results obtained with this project are not excellent and they will remain so for a while, at least until I regain a taste for it and improve.
Not finished but work in progress. I made a mistake in the calculation of the shadows because I forgot to integrate the height from the ground (located at -20). Use "z,q,s,d" to move (sorry those with a qwerty keyboard) and "space" and "v" to go up and down. I recommend setting Light Y to around 3000000 to simulate the Sun. I'm trying to create a lighting engine.