Urho3D is a game engine made by developers, for developers. The code is clean and well-commented. Urho3D is free and will always be free. There is no hidden royalties. It is IDE-agnostic and has no vendor lock-in. Urho3D runs on Windows, Linux, macOS/iOS/tvOS, Android, and even on Raspberry Pi. It also runs on your browsers. You need an installed Urho3D library for the desired target platform to proceed.