Building a level in the Bonsai Voxel Engine [video] (youtube.com)

The engine's completely bespoke; I wrote everything from the memory allocators and the font rasterizer to the renderer and level editor.

Source code is available online, and there's a discord for those interested.

Github : https://github.com/scallyw4g/bonsai

Discord : https://discord.gg/hv8NWrGU