Xenko

Xenko is an open-source C# game engine designed for the future of gaming. It comes with a full toolchain and is especially well suited to creating realistic games but allows you much more! The program effort is proudly supported by Silicon Studio Corp, a 16-year-old technology and services company of 300+ employees, dedicated to driving entertainment forward. Silicon Studio develops world-class products to help developers maximize the potential of leading-edge digital media technology.

Features and Highlights

VR ready
Xenko's clustered forward rendering, with its multisample anti-aliasing, makes it ideal for VR. Enabling VR is as simple as a single click. The Game Studio uses a single API for every device, with native support for Oculus and HTV Vive (more devices coming very soon). It comes with a VR game sample that shows you how to implement VR gameplay, including environment interaction and teleportation.

Advanced graphics
With Xenko Game Engine, there's no need to be a rendering expert to make great-looking games. The engine does the work for you, so you can focus on the important stuff. The app's PBR materials, light probes, post effects, multithreading, and next-gen graphics API support deliver realistic graphics with outstanding performance. The flexible pipeline, accessible low-level APIs, and customizable shaders let you tweak the rendering as much as you need.

Game Studio
It comes with a robust toolchain that enables you to intuitively and efficiently create, manage, and modify all assets of your game. The suite of editors simplifies and automates common development workflows. Its nested prefab and archetype systems scale along with all editors and assets. The Game Studio has also been designed so that it can be extended easily. A plug-in system to help users extend the Game Studio is coming soon!

Reliable engine
Whether you're indie or AAA, It lets you focus on your ideas rather than technical concerns. It comes with a full set of modules dedicated to editing every part of your game. Each is provided out of the box and integrated into the engine. Modern C# scripting with shader and script hot reload lets you build prototypes and iterate fast.

Note: Free plan is for personal use or small business. No credit card required. Limited functionality. Requires .NET Framework.