Hytale is a sandbox game under development at Hypixel Studios, where I’m currently employed as a software engineer working primarily on the technology we use to create and drive NPCs in the game. You can read more about the game on the official blog.
It’s built on a proprietery voxel engine developed in-house using Flecs, a C/C++ ECS library. If you’d like to read more about the tech, you can find links to the official technical posts below.