Oh, I forgot to attach the link :)))
http://agile-values.com/
In the bottom there is a video that describes how to create a game session (you can either import stories from Jira, or create them manually)
If you don't want to see the boring video, the process is quite straightforward:
1. Sing up and Sing in (there is no email validation currently, so you can register whatever you want - testuser@testdomain.com would do)
2. Create new Game
3. Create or Import stories
4. Save & Finish
5. Go to generated link and share it with other developers (so they could join the same session)