* Make esc the exit or q the exit key, I couldn't remember X... if esc is already doing something in the right click menu that just means you have to make it contextual!
* Would be nice if the options in the title screen lit up when hovered or were somehow more interesting. Could use SlickFX to make them really neat.
* Not sure how I feel about the current note system. Definitely a great first step, but I still think it's a little clunky. I don't really like having to hit the number a second time to remove it. Not sure what you could do, though, with strictly the keyboard... maybe notes should involve clicking?
* Would be awesome (and tons of work) if you created a tutorial puzzle which walked the user through the list of instructions since there are a lot of them. You could either save some state on the HD saying whether the user already played the tutorial or make it skippable so it wouldn't get old.
* Back to the menu, I want to click those links! Not press keys! Going to the ingame menu, it's *very* hard for me to tell which difficulty is selected. I'm a little color blind so perhaps that's it, but I think you should make it clearer by making the selected one even darker. I also really encourage you to make those buttons light up when hovered because they just feel too static and unresponsive as is. Also the timer looks like a button too... a little confusing.
* I think the new board is in the right direction, but could be further improved. I would try to make it look more like your sound button.
* No more comic sans! Seriously you have every font in the world to pick from and you settle on comic sans?? You're going for the brushed metal look so pick a font that fits that (open up an Apple I app and just use one of those fonts...)
* Going back to the title, if you're board and buttons are going to have this metallic finish then you probably want your game's logo to match that, so I guess it should change from comic sans/yellow to something harder and more industrial.
* One nice thing about all this is that it will help you make your background... you just need to make it look industrial/gritty to match your brushed metal board/buttons.
* I don't think it should be possible to select the board before hitting Go!
* I don't think you should have a blank board to start... I was confused. Either have a timer count down to start for a default board or have the Go! button softly flash red to draw attention.
* Definitely need to add sound effects for feedback. If I write a number in I should hear something confirming wrong it was write or wrong, or at least that I wrote something in.
* I really like the sound it makes when you select a square.
* There should be sounds for right clicking, entering notes, etc etc
* Maybe add a sound to the timer so that it plays when a minute has passed or some relevant interval. That way I can get a sense of where I am without having to stop playing and look.
* Still not really liking how it shows me whether it was correct, makes it vastly easier.
Alright, I think I just gave you a lot of work to do! Haha, the game is really looking cool and I'm excited for the next version!