```ruby
class MiniMetro < Cask
  url 'http://static.dinopoloclub.com/minimetro/builds/alpha12/MiniMetro-alpha12-osx.zip'
  homepage 'http://dinopoloclub.com/minimetro/'
  version 'Alpha 12'
  sha256 '0c81781fff8984f41276fe2c9c0a1da7bdfd18c8970fbe4b8c4ff2376936e7bd'
  link 'MiniMetro-alpha12-osx.app', :target => 'Mini Metro.app'
end
```

Update Mini Metro to Alpha 12a
user
```ruby
class MiniMetro < Cask
  url 'http://static.dinopoloclub.com/minimetro/builds/alpha12/MiniMetro-alpha12a-osx.zip'
  homepage 'http://dinopoloclub.com/minimetro/'
  version 'Alpha 12a'
  sha256 'cbbf5e60c39bb4d850e65703e220d41a0410212fc6f87d997abe36dc2d7658f9'
  link 'MiniMetro-alpha12a-osx.app', :target => 'Mini Metro.app'
end
```
assistant