straight from their site

"Alpha contains many more features, concepts and game elements compared to the demo. However it is still work in progress and we are improving it." "This is the cutting edge "experimental" version. There might be some nasty bugs. Use on your own risk. Your computer probably won't explode though :). "

compatible with OSX Snow Leopard, Lion, Mavericks

be warned that this IS the EXPERIMENTAL version!

if you want a stable release check my other torrents for current version 0.9.8 (alpha)