Stride (formerly known as Xenko) is a free and open-source C# game engine. It is growing quickly and is supporting multiple platforms, with more to come.
News can be found here.
Ranked in these QuestionsQuestion Ranking
Pro Good looking and fast
Looking nearly as good as Unreal Engine 4, but rendering significantly faster.
Pro No royalties or licensing fees
Pro Projects are normal Visual Studio solutions
No proprietary project format, so it works with all the official .NET tooling.
Pro Supports Visual Studio
Pro Very modern render engine
Pro Powerful 3D Rendering Engine
Supports Vulkan. You can achieve good quality as in Unity3d and Unreal Engine
Pro Straightforward editor
Stride provides a simple and clean working environment for designing games.
Pro Community seems friendly and is growing
Pro Engine AND Scripting are both C#
Since the engine is written in the same language as the scripting, there is no weird mix of technologies as other engines have.
Pro Supports Vulkan
Currently the only well known open-source game engine that supports Vulkan, and probably one of the only.
Pro Easy to learn and use C#
Pro Multiple Starter Templates
The engine comes packed with multiole example projects to help you get started.
Con No terrain editor
Unless you like working on planes, there is no terrain support.
Con Editor is Windows only
Since version 1.7, Linux can be targeted for runtime. The editor for the engine is available only to Windows though.
Con Small user community
Unity and UE have a vast amount of user community.
Con Does not currently support Playstation or Switch games
Con Iteration may be slower than with other engines due to longer "build" times when certain changes are made
Con Shader system require's overhaul
Shader's are not easy to get to grips with and Stride's shader system. Needs overhauling for easier use.