O3DE

O3DE is a real-time, open-source, high-fidelity project-oriented 3D engine, where you can design everything from AAA video games to simulations and robotics. This software features an integrated set of authoring tools, physical rendering, and extensible modular systems that will make your life much easier when creating exactly what you're looking for.

A state-of-the-art renderer

O3DE includes Atom Renderer, a modular, multi-threaded, modern pipeline-oriented rendering engine that supports techniques such as Forward+/Deferred and data-driven pipelines. Atom is designed to achieve physically plausible graphics, take advantage of modern CPUs/GPUs, and allow teams to modify or replace key parts of the pipeline without rewriting the entire engine. This facilitates both cinematic quality and scalable performance across devices.

Work with modular architecture

This tool is organized in modules called Gems (self-contained packages of code and/or assets) that projects can activate or deactivate as needed. This approach allows you to build a custom engine, as you can use only the parts you want, create your own Gems, and share extensions without touching the core. The module system makes collaboration easier and reduces complexity when integrating third parties.

Comprehensive visual editor

O3DE includes a visual editor with tools to build scenes, edit levels, manage prefabs, process assets, and create UIs in real-time. The Asset Processor converts and optimizes resources for runtime, and there are also integrated tools for animation, cinematic editing, and visual debugging, designed for a professional workflow between artists and programmers.

In short, if you're looking for a good, free, and open-source 3D game engine, download O3DE, the all-in-one tool that has everything you need to design games, for free.