Thanks for the feedback oNyx. Some of the guys on the GTGE forum also thought it was a little difficult at the start, so I have changed the first few levels to 4 colors to make it easier to find matches. I also changed some probabilities for the special tiles to make 'good' things happen more often at first.
The theme is also a tad too dark (imo anyways).
The scoreboard area closely imitates a blues concert poster I found on the net. As far as the background behind the tiles, I actually tried some lighter colors, and they just didn't work as well. I made the tile images before I had the Blues theme, so it just got stuck that way. I would like to eventually change the tile images and background to match the Blues theme a little better. Maybe when (if?) I get around to that, I'll experiment with some lighter/brighter colors.
Thanks again. And by the way, <shameless plug> Four Square Blues is today's featured game at http://www.gamespotter.com
. </shameless plug>