Nice job! Game is simple but it is well put together. 

Simple but cool game imo
Liked that you added a particle effect to the lava
I also found the graphics quite cool due to their simplicity.
By the way there is a mistake in the controls screen ;)
And the sfx of the smashing rocks didnt always play

The controls are quite responsive, the game is straightforward but it works well. The graphics are simple but fun. One point to improve would be the music, which I find too repetitive. Good job ^^