the lava eruptions are amazing, i've never seen such good particle effects in here. *maybe* add a heat distortion shader, but that's all you could improve about it.

about the panels/ HUD: have a look at the stamina panel in the newer super mario games. kinda like that... http://fallingsky.blogs.com/falling_sky/super-mario-galaxy-20070308014605100.jpg or that http://www.myds.com.au/img/gallery/full/LJSLMD3W.jpg . i think something circular would fit in.