Interesting game. I've already finished nearly half of the levels in a little over two hours (and I am sure some of that was time away from my computer or watching something momentarially-as lately I have been watching YouTube in the background.
I say 'finished' half of the levels because some, if not many of them I didn't even rank in. I have more copper than silver and more 'check marks' (i.e. finished, but did not rank) than gold (and likely silver).
But the poor 'what exactly do I need to do to rank copper, silver or gold, isn't really the problem... anyone can figure that out after playing a level a few times... no, the problem I found is that in the labratory levels, specifically playing Nitroglycerin, if you start the second level of without directly beating the prior-and even then sometimes-your will immediately explode, restart the level and repeat. Even that can be a simple error in coding, not spawning the liquid correctly, or the game assuming the liquid is moving too quickly as it 'jumps' into existance... but when you get to the Body levels, and specifically the blood levels I constantly get a divide by zero warning. This doesn't crash the game, but it does freeze it until I 'windows key' out and click 'ok'.
I haven't gotten past these levels yet, as I fet it inportant to add this to a review. If you are programming anything you really NEED to make sure you don't have code divide by zero. Usually it will completely crash software (ah, the blue screens of old), and I'm not entirely sure how this software is able to cope with it.
The game looks finished and even polished, until you reach the bugs that clearly show it is not. It is still fun to play, and for those who feel the need to get gold on everything you'll have a challenge... but they really needed to go over their software and make sure things worked correctly, each time, for all hardware.
(A FYI, I'm on an HP Pavillion 7000, with Intel I7 and nVidia GeForce 630M, running WIndows 7--so it isn't like I'm trying to run the game on obscure hardware or software).
EDIT: So, I've had to 'skip' some levels... Space is hard, and the level just before also has the divide by zero error...