Refreshingly different
I've been getting very lazy writing reviews for people's works recently - a lot of the stuff I've scanned through for the last month has been pretty dull and hasn't inspired me to do any more than voting.
This however is a refreshing change from a lot of the mundane stuff I see passing through the portal. It isn't a particularly difficult feat to tie sound effects to mouse locations on the screen, but what I like is the sounds overlay in a way that is realistic - those who have played "Shogun - Total War" will instantly recognise this instrument and spend at least a good couple of minutes playing.
I also liked the fact that you didn't resort to CLICKING on strings to make sound. As you probably figured out that would've been no fun to do at all. Obviously the down side is you can't easily play strings in the middle of the instrument without playing ones next to it. If you wanted to fix that, maybe you could've assigned keys on the keyboard to different notes (e.g. "Q" through to "P"), so the really keen player could try mastering this even better.
By way of more constructive criticism, there could be the possibility of a tremolo on the strings, to create different sounds.
Finally, I think as well as those technical flash development suggestions, it would be worth thinking what your ultimate goal is with this, i.e. what does the final product look like. If you want to create a music playing game whereby the player strums to music, the development would be very different from if you wanted an entire orchestra that the player could play around on. I'm aware this is a Beta at the moment, but i don't understand what your vision is in the long term, so it's very hard to provide constructive criticism towards that. Maybe it would be worth putting that in your Author's Comments.
To sum up, this was extremely refreshing to see and i really liked playing with it. I'd like to see more development around it in terms of ease of playing, possibly some instructions on how it's played, and definitely some kind of expansion, either into a game format, or more instruments.
Really nice, and let us know if you make any significant developments!