UrhoSharp is described as 'lightweight Game Engine suitable for using with C# and F# to create games and 3D applications. The game engine is available as a portable class library, allowing your game code to be written once and shared across all platforms' and is an app in the Development category. There are more than 25 alternatives to UrhoSharp for a variety of platforms, including Windows, Mac, Linux, Online / Web-based and Self-Hosted solutions. The best alternative is Godot Engine, which is both free and Open Source. Other great apps like UrhoSharp are Unity (Free Personal), Wick Editor (Free, Open Source), CRYENGINE (Free Personal) and ENIGMA - LateralGM (Free, Open Source).
Godot is a fully featured, open source, MIT licensed game engine. It focuses on having great tools, and a visual oriented workflow that can export to PC, Mobile and Web platforms. It is a cross-platform 2D and 3D game engine and game development IDE.
The Wick Editor is a free and open-source tool for creating games, animations, and everything in-between. It's designed to be the most accessible tool for creating multimedia projects on the web. Your creations can run on any device with a web browser - that means mobile too.
Open 3D Engine (O3DE) is an Apache 2.0-licensed multi-platform 3D engine that enables developers and content creators to build AAA games, cinema-quality 3D worlds, and high-fidelity simulations without any fees or commercial obligations.
One framework for creating powerful cross-platform games. The spiritual successor to XNA with 1000's of titles shipped across desktop, mobile, and console platforms. MonoGame is a fully managed .NET open source game framework without any black boxes.