[yodon]

Are there other courses laid out like this? This looks fascinating!

[Thorrez]

https://xss-game.appspot.com/ (this has a lot of overlap with gruyere)

https://github.com/cure53/XSSChallengeWiki/wiki

https://sites.google.com/site/infosecrocks/ (this links to some of the other stuff I mentioned)

https://www.hacking-lab.com

There's also these 2 advanced XSS challenges:

https://alf.nu/alert1

https://prompt.ml/0

I'm not sure if they're still functional, I think some of their solutions require functionality that browsers have since changed.

You might also want to check out the Youtube channel Live Overflow:

https://www.youtube.com/channel/UClcE-kVhqyiHCcjYwcpfj9w

[uzakov]

Another web and mobile application security training platform: https://github.com/OWASP/SecurityShepherd