下までサクサク進んだけど、起動してアクセスすると、下記のエラーを吐く
Application.index action not found scala play
コメントに原因と解決方法を書いた

%cd /usr/local
%brew versions scala
2.9.1    git checkout b78cfbd /usr/local/Library/Formula/scala.rb
2.9.0.1  git checkout cb1ab23 /usr/local/Library/Formula/scala.rb
2.9.0    git checkout 4002978 /usr/local/Library/Formula/scala.rb
2.8.1    git checkout 0e16b9d /usr/local/Library/Formula/scala.rb
2.8.0    git checkout fdb41a3 /usr/local/Library/Formula/scala.rb
2.7.7    git checkout 6a18e38 /usr/local/Library/Formula/scala.rb
2.7.6    git checkout a82e823 /usr/local/Library/Formula/scala.rb
2.7.5    git checkout e9dd256 /usr/local/Library/Formula/scala.rb
%git checkout 0e16b9d /usr/local/Library/Formula/scala.rb
%brew install scala
%scala -version
Scala code runner version 2.8.1.final -- Copyright 2002-2010, LAMP/EPFL
%brew install play
%play install scala
%cd ~
%play new test --with scala
%play run test