Marionette Studio

Java framework providing unified API for building 2D or 3D games across desktop, mobile, and browser platforms, with hot code swapping, rapid prototyping, modular architecture, integrated physics, input, asset tools, and support for desktop-native debugging.

Urho3D is a lightweight, cross-platform rendering and game engine implemented in C++ and released under the MIT license. Greatly inspired by OGRE and Horde3D.

Construct 3 is a powerful 2D game development engine which uses Scirra's intuitive event system to allow its users to build all kinds of games and apps.