Does Chime strike a chord with the PlayDevil reviewer? Here is a snippet from the review:
"Even after shapes are made their ‘shadow’ remains. This shaded area or ‘coverage’ is vital as only by covering sixty percent of the play area are new levels/boards unlocked. This is really the ‘goal’ of the game during the timed mode (three, six or nine minute settings). While score still plays in to this mode (and in the online rankings) the real aim is to reach this sixty percent coverage on each of the five boards."