Sound and music is probably one of the most overlooked areas of new hobbyist game developers.  Just adding a cheesy soundtrack and cute hopping and squishing noises subtly changes a boring, simple game into one that feels professional and complete.  The funny thing is that usually this process is completely subliminal with most people not realizing the difference sound makes.  Even great games can be vastly improved through the use of audio as anyone who has completed Portal can tell you. 

PGC allows you to upload your own music and sounds as .WMA or .MP3 files to use in your games.  You can find a “How To” explaining the process of uploading and playing back audio on the Popfly wiki here.  There are many programs which allow you to record audio on your computer from very basic programs (Windows Sound Recorder) to very advanced interface/software packages such as Pro Tools.  However, this all assumes you are in possession of musical instruments, recording equipment and are musically capable or willing to invest the time to become so.  That’s a lot of commitment for most folks.

While I can’t help you with the becoming musically capable part, I recently dug up a free program called Finale Notepad which I had played around with during my freshman year of college.  The full version of Finale is a professional tool for creating music scores on the computer.  At least back when I first used it, it was pretty much the standard for creating music notation.  The Notepad version probably isn’t full featured enough for that crowd, but it’s great for composing simple songs which can then be exported as MIDI.  MIDI is an electronic format which isn’t an actual recording, but rather the instructions to synthesize a piece (what notes to play, what synth instruments to use and when to play them).  As such, it’s a great tool for making retro game music, because that’s exactly the kind of music that was used back in the 8 and 16-bit days of Super Nintendo and Genesis.  I usually just play around on the staff in the key of C to get what I want, but I believe you can also hook up a keyboard to record the notes.  Even if you aren’t musically inclined, you can probably put together some basic tracks by trial and error.  Once you’re happy with your piece, just click File->Save As… and change the file type to MIDI. 

Since PGC requires files to be of type .WMA or .MP3, you’ll now have to convert the MIDI file.  The easiest way I’ve found to do this is to change your recording device to “What You Hear” in the sound settings in control panel.  If this option isn’t available (I think some drivers don’t support this option) like on my work machine, an easy workaround is to plug a cable into your headphone jack and back again into the microphone jack on your computer.  You may have to play around with the volume settings to get it just right.  Once you’ve done this, you can easily use Windows Media Player to playback the MIDI and Windows Sound Recorder to record a WMA file (Vista) or a WAV file (XP) which you can then convert to a WMA or MP3 using a tool like CDex.  There might be an easier way to do this – if so, let us know in the comments.