Although the menu does instruct the player to find blue boxes, there appear to be very few of them, making it extremely difficult for players to not only progress, but also internalize the fact that they're looking for those blue boxes. You could honestly have a high level of difficulty with less confusion by placing some more boxes and reducing the amount of health they give. Still, the atmosphere created by the music and the visuals is quite amazing. The feeling you create with just simple squares as particles is fantastic.