Personal record: 27 (fifth try).
Personal record with eyes closed: 12 (didn't try too much this way though).
Personal record of response time at 10 hits: 102.
One of the sequences I had to follow was Yellow, Blue, Yellow, Yellow, Yellow, Yellow, Yellow, Yellow, Yellow.
I play remembering the notes as groups of 4, and after hearing the whole sequence, I replay it following a fast but consistent rhythm for each group of notes. If I need to think the next pattern, I stop some milliseconds and continue.
It's not very good to try to do it very fast, after some time you may be not sure of the keys you have to press, or you can mess up yourself and end up mashing the arrow keys.
It would be nice if you added alternative controls (WASD keys), because the "up" arrow from my keyboard is broken, so I have to click the green button if I ever have to use it.
Also, I don't know whether the problem is my computer, my Internet connection or whatever, but I can't upload my highscores. I can't even see the scoreboard, and I want to know if I'm good at this or not! :(
Another flaw I found is that, if you lose, and press the "Play" button too early (when it's still "invisible"), that button (and the "Play more games" one too) will freeze, forcing you to refresh the page.
Despite those little points, the game is flawless as far as I could see. It's simple but cleverly designed, the graphics are excellent, and the atmosphere you created is perfect for this kind of games. The background sound also helps very much to focus on the game.
Thanks for filling a new space in my Favorite Games' list.
And kudos to MrRubix. o_O