Materia - Materia is a development environment to build advanced mobile and web applications.
Game Center - Game Center brings social gaming to OS X and iOS apps.
Zukitwo - Zukitwo is a Gnome Shell and GTK theme that currently works on Gnome Shell 3.14 and the latest version of GTK.
GameStreamer - Connection people and games anywhere.
Papirus - Papirus icon theme for Linux. Contribute to PapirusDevelopmentTeam/papirus-icon-theme development by creating an account on GitHub.
OpenGameArt.org - A site dedicated to sharing artwork & other assets for game development.