Audio Setting Option

I like to listen to music or watch video while playing games. The bgm is too loud there doesn't seem to be a way to change that. Can you add an option lower or mute the in-game sounds? I'd really appreciate it if you can?

You can mute the in-game sounds by pressing F1 while the game is open and deselecting the Play BGM and Play BGS options. If you wish to lower the volume, you could try using the volume mixer on your computer to lower the sound level output by the application.