An idea for a sandbox style iseki roleplay just popped into my head and I had to get it down to see if anyone would be interested, or had any ideas of how to go about it?  

Basically like any iseki our characters would die, and end up in a whole other would, a multiverse, but what makes it different than others is that the heroes and villains (in media) don't exist, anymore.  As they were all killed off with their powers or abilities, or items taken and implanted in special crystals which people can equip in order to gain said abilities/ items/ skills/ etc/ etc....

So here's some questions for people
-What kind of limits should be placed on the crystals?
-How should these crystals be dispersed?
-Would this work better as a sandbox or limited roleplay?