GoatTracker - This is a crossplatform C64 music editor.
Unity - The multiplatform game creation tools for everyone.
OnlineSequencer.net - OnlineSequencer.net is an online music sequencer that allows users to create beats and music tracks.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Jummbox - A modified Beepbox that have more stuff then Beepbox. It can be used just like Beepbox. The features of Jummbox is the same of Beepbox's features, but Jummbox have more stuff to offer.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.