Speaking purely from personal preference, if a game has good music, I leave it on. The main problem with any game (not just ones made with BYOND) is that while the music may be nice, it doesn't provide appropriate atmosphere.
Also, I'd suggest avoiding any actual lyrics; they can detract from the experience itself and detracting from the experience is the LAST thing you want to do.
Remember to make sure your music fits in the context its used. For example, look at the theme for Requiem for a Dream. That, at least to me, would be excellent for an end-game (literal or metaphorical) boss fight.
In short, yes. Just be very careful and examine the context in which the music is used to provide the best possible atmosphere.
Also, I'd suggest avoiding any actual lyrics; they can detract from the experience itself and detracting from the experience is the LAST thing you want to do.
Remember to make sure your music fits in the context its used. For example, look at the theme for Requiem for a Dream. That, at least to me, would be excellent for an end-game (literal or metaphorical) boss fight.
In short, yes. Just be very careful and examine the context in which the music is used to provide the best possible atmosphere.