The MOGG file extension is for Multitrack Ogg files. These files store OGG audio tracks separately. This allows tracks to play together or independently. MOGG files are used by games like Rock Band and Guitar Hero. They contain different musical parts on separate tracks. This lets parts be played together or separately.
MOGG files can be opened with Audacity and some other audio programs. Some MOGG files may instead store MedCalc data. MOGG is an audio container format for OGG sound tracks. It can possibly convert to other formats if software supports MOGG. It was likely created with Audacity. MOGG files associate with Linux, Mac, and Windows.