Antares can play music in the background during the game. It supports music files in module file formats.
No. You can use music from the factory scenario (as most plugins do).
Music is in the music directory and has a .s3m or .xm extension.
These songs are used for in-game music in the factory scenario:
The factory scenario also includes the following songs, which are used in other situations and generally not in-game:
(Many thanks to Aurel for uploading the Ares OST to YouTube!)