Finally, I've completed the Earth VS Steel chapter. Here it is, it only goes up until you take control of Chronic in Me Against the World. That chapter will take far less time to complete, I only have to place enemies and get a few scenes set up so expect that one soon. Anyway, the Earth VS Steel mission IS timed, so remember that you can pause the game with D, so in case you need a break from the Timer (which runs during battle) and use Shift for running. You only have forty minutes to complete Earth VS Steel and there are six things hidden in it. Five prisoners are hidden in the factory (only available during Earth VS Steel) and finding all five will net you the Cypris Tablet, which will do something as soon as I finish the Secret House. The sixth thing is Sphinx, who is hidden somewhere to give you a Super Shard. You need four of these with the Ancient Crown item to unlock a special mission through the Secret House.
I still recommend checking out the other tribes, specifically the Water Tribe, where you can find the King of Games, Reaper, who could possibly give you an excellent, excellent item.
Here it is:
Chaos Spirits 2: Chapter 2 Earth VS Steel