I really like the idea behind this game, though once you get into the rhythm... it gets difficult to lose. It doesn't seem to progress any faster, or the bar sink any lower, after a certain point. Just grind, grind, grind... a little intensifying pace would be good past a certain point. Also doesn't seem right that you get a 'Game Over' if you manage to bring down a row that goes all the way up to the line (for example if you drop a lava on a pile of stone you get a 'Game Over' even as you see it sinking to the bottom). Also bit long pause at the time when all rows but the bottom three are taken away - with no message or effect as to show what's going on. Just a few things I notice...
I love the gameplay otherwise, the intuitive play with elements, and the down button was a much appreciated addition! :) About the title... it's simple, but only gives the 'one side' to the elements, kind of strange name when you start thinking about it. Overall nice work, a simple but addicting idea; hope it'll be polished to the best point possible!
-cd-