As the title states, I'm making a guitar hero style mini-game. For does of you who don't know what guitar hero is, it's a fairly new video game available for ps2 and xbox360. It is very similar to DDR (Dance Dance Revolution).

Now my problem lies in how I should actually create the core of the game, the system if you will. I was thinking of running a loop check that randomly creates frets that will, one created, slide down to where you much hit them with the keys that I will set.

That part I can understand, but I'm not sure how to tell the user to click when the frets go down to the bottom where they must be hit or else you fail. Any suggestions?