Godot Engine - Feature-packed 2D and 3D open source game engine.
LTSP - The Linux Terminal Server Project adds thin-client support to Linux servers.
GDevelop - GDevelop is an open-source game making software designed to be used by everyone.
Thinstation - Thinstation is a basic and small, yet very powerful, open source thin client operating system...
MonoGame - MonoGame is an open source implementation of the Microsoft XNA 4 Framework.
Nakama - Nakama is an open-source distributed social and realtime server for games and apps.