Ubuntu Lucid Alpha 2 has just been released and a new addition is the mind puzzle game gbrainy.
You can read more about the latest release in a blog post by Jordi Mas (the author).
gbrainy is a great game and we want to find any problems before final release so please try it out! If you don't already have it installed then you can get it from the Ubuntu Software Centre (search for gbrainy).
If you find a problem the best thing to do is file a bug in GNOME. If you don't have an account on GNOME Bugzilla but do have a Launchpad account you can file a bug against Ubuntu. I am working on getting the "Report a Problem" menu entry into the help menu which will make this even easier!