I have been playing this game on mobile, and I noticed that there was no way to purchase upgrades. It would be nice if there was a purchasebutton after selecting an upgrade so mobile players could use them also. And another thing; from reading others comments, a few ideas to make a better harder version. Having something like a water cluster where when it is destroyed, it makes smaller droplets; a possible 'gust of wind' where the grill loses its auto abilities for a few seconds, maybe a thunderbolt which makes drops more relisilient and needs more hits to be destroyed.
I have too many ideas, so if you ever want to read a page of possibly bad ideas, I'm your guy.