What is expert mode in shadow the hedgehog

Getting all A's on every level will unlock Expert mode. This includes character commentry [eg. Rouge on a lot of levels], more enemys, harder enemys, harder and longer levels, but most importantly-a homage to the original Sonic games. Run out of lives and you have to start again from the beginning [you don't start the whol expert mode again, just the story your working on]. Devil Doom is also about twice as powerful and has the ability to use Chaos Control to stop time [this is done very rarely, about once in every 5 battles].