Serious potential..
When I initially looked at this submission on Newgrounds I was asking myself "What is the point?" However, after going to the Official site and looking at what you did in full-mode, I must commend you on your efforts. I see several uses:
1. A musician can use this as a reliable easy way to tune his guitar-
So that leads me to request: Could you integrate a tuner into your full flash module? I have seen flash guitar tuners on the Interweb but few with as much potential functionality as yours can potentially have. Go for it!
2. Interactivity- While I do not program flash, If you could create a version of this utility which can actually interact with a real guitar connected properly to a computer [yes THAT is a feat in itself I know! ] This utility could go from useful to very marketable. You could find yourself making a lot of money if this module were downloadable, and could actually attempt to teach, correct and interact with a properly connected instrument using a high end sound card capable of handling music instruments such as Creative X-Fi Elite]
3. Complaints - I only had one. What is the purpose of having the guitar interface inverted? [Low E string facing downward, treble strings up?] Maybe you were trying to put "personality" into the look of your guitar by using a visual design that might honor Jimi Hendrix, but this does no favors to the majority of playing musicians. Maybe please put the guitar right side up? Everything else is a 5 star rating here. Great job, sir.
Conclusion
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I've played music for 12 years. If you added some of the above features, I would be willing to spend the money to buy it. I would expect with the work required to make it happen that the price may be high. Regardless, to me it would be worth buying.
Titan out.