A loop of "classic.mp3". Fact: ".s3d" is a file format for Scratch 3D projects. ".bld" is a preview file format on builds 0.1 to 12. ".s3dp" is only used in build 86 and 99 which is used to create "download projects" in other builds but took the primary for Scratch 3D projects in these builds. ".sprt" is the sprite file format.
