OpenDeck is an open-source desktop application designed for use with Elgato Stream Deck and similar devices.
It is cross-compatible with plugins developed with the Elgato Stream Deck SDK and runs on every major desktop platform.
Emergent (alpha)
Emergent is an open-source web-based versatile game engine.
It supports scripting with JavaScript, and thanks to its Git-based version control support, you can access your projects from anywhere.