The Hyperledger Composer playground has been deprecated, so the playground does not work anymore, still you can watch the videos to get how the hyperledger works. Other than that, the course is still a good package of knowledge.
Sadly there is not easy replacement, since its a deprecated project the only way you can try it is by deploying it through a local instance in your computer.
https://github.com/hyperledger/composer/blob/main/README.md
Carlos Z
Hi @filip, I took this course this 2021. Are there new updates about this hyperledger or still under development? This is very interesting.
We have plans to launch a Hyperledger course, but it could take us time until we finish other projects that we are working right now (check all the latest course that we have been launching over the past weeks).
But for sure we will update all our courses in the proper time. 
Carlos Z
Hi @filip and @thecil and everyone,
I took a quick look on Hyperledgerâs composer page on their site and since they mentioned composer being deprecated, they suggested using Fabric v 1.4+ as a replacement. Any chance you will update this course accordingly? Thanks
Unfortunately there doesnât appear to be a âplaygroundâ available. Iâve tried loading an earlier version of the link in the hope something was still available, but alas, no dice.
If thereâre similar alternatives to have a play around via a browser, please do let me know. Thank you!
Hello @filip
When will the Hyperledger Composer be availble? Please let me know if there is an alternative.
Thanks!
Commenting here to be updated when HL Composer or any other Layer or Platform can be used. Thanks! 
waiting for the Update!!! and enjoying the content !