From the faq (
http://game-editor.com/docs/faqs.htm):
"Why I can't use mp3 files?
Due to patent issues, the MP3 support has been removed and Ogg Vorbis implemented to all engines.
If you use MP3 in your game you must pay royalties to Fraunhofer Institut.
Read more at: mp3licensing.com
The Ogg Vorbis is a royaltie free music format with superior quality over MP3 format.
If you use MP3 in your games, you must convert to ogg format. "