Open source Hearthstone-like game, except it's real-time (no turns), and it's space-themed: https://github.com/lacker/cardkit

It's an effort to learn more about react.js, Webpack, babel, and ES6. Contributors welcome. It should be easy to build and run. We have a Slack channel for people who have contributed.

You can play the basic game (if you have an opponent) at http://spacetime.tv (very much a work in progress)