OpenAI Gym is a much better alternative to this. It's better in every way and more importantly you're not just giving away all your hard work for free.
I wonder how much code one needs to port to be able to use another language?
We have a lot on our plates right now so adding new languages isn't the main priority, however we add languages based on the number of upvotes on suggestions in our dedicated forum thread
https://www.codingame.com/forum/t/please-add-the-following-p....
Do not hesitate to go there and vote/ask for Common Lisp
https://www.codingame.com/forum/t/please-add-the-following-p...
I've not used it yet but I hope to soon!