JPHP - an implementation of PHP on Java VM
Open-source, cross-platform, game-development tools
A continuation of the popular Artemis ECS framework
Test project with a 2D platform game developing in Godot 3.1
Build Cross-platform Applications
Asphyre is a cross-platform framework for Delphi and FreePascal.
A cross-platform interpreter for many point-and-click adventure games
A JavaScript game library to quickly develop board games for the web
3D .NET engine for Windows, Linux, Mac
LEGADEE (LEarning GAme DEsign Environment)
Java based Open source Voxel Engine for RTS games