Thanks for playing and your feedback! Sure, will consider color coding the cells.
Oops! I should redesign the tutorial I guess, if folks are getting stuck there. Hope you finish it sometime. You could also skip that level and move to the next one, or the main game directly :) You've done most of the tutorial, so hopefully you'll be fine.
Thanks! And your game is interesting as well. Played a couple of levels yesterday. Will spend some more time and drop a review soon.