As someone who is still learning to code and is often doing so in a situation where I don't have access to my local files or a code editor (hint, hint, at work during my downtime on the organization's device), I've been using a similar in-browser editor to test ideas or work on my projects. I recently "discovered" repl.it because I needed an editor that could run Python or Node.JS in browser as I shifted my learning away from the front end HTML/CSS/JS combo. Repl.it has a ton of languages to choose from- even some "toy" languages like LOLCode. Even better, they just leveled up their Github integration.
I am pleased to find out that today they began rolling out "Repl from Repo", which allows you to run repos within Repl! It looks like they're still fleshing out the functionality, but it sure does feel good to have another avenues to run my projects and build them in scenarios where I don't always have access to my personal device or files. Even better, all of the repos where I'd have to download them and configure an environment are also able to be run through Repl, so I can easily try out cool looking repos from all types of languages without the commitment of a full on download.
You can now also add a "Run it from repl.it" badge to your README.md's on Github, which gives folks an instant link to run your project! Try it here with a game of Minesweeper. Be sure to click "Run" once repl.it compiles the project.