Playing songs while making your Game

[Evil Yoshi Toes]

I always listen to music while I work on my art. I've found that it keeps my mind from straying.

As for how important it is in a game/level, I'd say it's very important. A level can feel extremely empty without music. Music adds atmosphere! Actually, sometimes a lack of music provides successful atmosphere, usually an eerie or peaceful one depending on what ambient sounds are provided. Dead silence is almost always uncomfortable in a video game but that could also be effective if there are still sound effects the player can cause (like footsteps and such). If there's no sound at all I'd probably assume my speakers were broken and I'd find it very unenjoyable.

Also, the wrong music can be just as bad as no music (or worse!). Having energetic music like the athletic theme of super Mario world in a cold and dreary level would be very annoying and would ruin the whole level. Music has a lot of power.