Urho3D

Allows free use, modification, and distribution in commercial projects without royalties, as stated in the license section.

Designed for minimal resource usage, making it ideal for indie developers and projects with limited hardware, as emphasized in its philosophy.

Runs on multiple operating systems and architectures, including web deployment via compilation for browsers, as highlighted in the features.

Provides built-in support for both 2D and 3D graphics, simplifying development for mixed-media games without separate engines.