Tuxblocks-Cross Platform PlayN Game
Tuxblocks is cross platform java game which helps students to learn algebric equations,solve algebrs equations,create algebric equations as well as very nice arcade game comes with it.it was developed by Thomas Price in GSOC-2013 project. I have tested it on Linux,Chrome,Chromium,Firefox,Iceweasel and Android. It is fantastic and very smooth to play.i can write more and more about it but i think i should provide link to you so you can describe it by urself that how good this game is.
Web version: http://tux-blocks.appspot.com/