As I mentioned before, I was going to make a little post about the development of my alternate Playground.
The biggest news is that you can use the top 100 or so crates now, but there's also Clippy integration and a simpler editor for accessibility / mobile / security conscious users. Thanks to @stebalien, @leonardo, @comex and @cuviper for the feedback and suggestions!
Nice! May I try to crash it?
It depends! I'm more than happy to have holes in the sandboxing found and reported. I don't have any money for a bug bounty program, so all you can get is Open Source credit 
If you think that you are really likely to break it, I'd be happy to set up (or help you set up) a test server to attack; keeping the primary one usable by others. You can also run it locally which might make it easier for you to experiment.
I don't think I'm likely to break it too badly, I just want to try a few obvious attacks.
Awesome job with adding in external crates! Now it will be much easier to showcase external rust-nursery libraries like regex.
Apologies everyone, I succeeded in crashing it.
Haha, it was only a matter of time! Would you mind sharing what you did so we can fix it? (Ah @sorear messaged me privately — thanks!)