I've copied my game into the app wrapper and it runs fine with ruby Main.rb, but when I try to run RubyGosu App in the Mac OS directory, it complains about stringio.bundle:

<internal:lib/rubygems/custom_require>:29:in require': dlopen(/Users/Andrew/workspace/sevenstars/RubyGosu App.app/Contents/Resources/lib/stringio.bundle, 9): no suitable image found.  Did find: (LoadError)
  /Users/Andrew/workspace/sevenstars/RubyGosu App.app/Contents/Resources/lib/stringio.bundle: no matching architecture in universal wrapper - /Users/Andrew/workspace/sevenstars/RubyGosu App.app/Contents/Resources/lib/stringio.bundle
  from <internal:lib/rubygems/custom_require>:29:in require'
  from /Users/Andrew/workspace/sevenstars/RubyGosu App.app/Contents/Resources/lib/yaml/syck.rb:6:in <top (required)>'
  from <internal:lib/rubygems/custom_require>:29:in require'
  from <internal:lib/rubygems/custom_require>:29:in require'
  from /Users/Andrew/workspace/sevenstars/RubyGosu App.app/Contents/Resources/lib/syck.rb:9:in <top (required)>'
  from <internal:lib/rubygems/custom_require>:29:in require'
  from <internal:lib/rubygems/custom_require>:29:in require'
  from /Users/Andrew/workspace/sevenstars/RubyGosu App.app/Contents/Resources/lib/yaml.rb:16:in yamler='
  from /Users/Andrew/workspace/sevenstars/RubyGosu App.app/Contents/Resources/lib/yaml.rb:43:in <top (required)>'
  from <internal:lib/rubygems/custom_require>:29:in require'
  from <internal:lib/rubygems/custom_require>:29:in require'
  from /Users/Andrew/workspace/sevenstars/RubyGosu App.app/Contents/Resources/lib/chingu.rb:27:in <top (required)>'
  from <internal:lib/rubygems/custom_require>:29:in require'
  from <internal:lib/rubygems/custom_require>:29:in require'
  from /Users/Andrew/workspace/sevenstars/RubyGosu App.app/Contents/Resources/Main.rb:1:in <top (required)>'
  from <internal:lib/rubygems/custom_require>:29:in require'
  from <internal:lib/rubygems/custom_require>:29:in require'
  from /Users/Andrew/workspace/sevenstars/RubyGosu App.app/Contents/Resources/gosu/run.rb:11:in `<main>'