This games (and doodle god) starts off fun, but after a while there are too many elements to try to combine, and it becomes tedious and frustrating.
This could be easily solved by highlighting 'final' items separately, so you never need bother trying to combine them.
I liked this game to begin with, it's original and the atmosphere is cool. The trouble is it becomes quite tedious guesswork after a while.
What might make it more fun is to split it into levels, so that you basically have the same game several times from different starting points, but shorter. Another idea might be to have 'dead' items fade out, so that you don't keep trying to mix them with things. Basically something to reduce the possibility tree from blossoming quite so fast.
I like the progress bar that tells you how many points you have for the rounds target, but it would be improved by having a line on it for the points you should have for each go, so you can see if you are on target.