first of all - chrono trigger = awesome game, i'm playing it now. then yeah, it's a fantastic concept but it is impossible to make (at least for now). for example, look at skyrim: one era, big world, many bugs. imagine now 5 eras: bugs are increasing logaritmically: manybugs*manybugs*manybugs*manybugs*manybugs = totally unplayable. the only solution that i see are the semi-random progressive generated content, like quests, npcs, items, and maps. something like this is possible, but it requires too much effort. but partially, you can find these features right now: minecraft=random terrain, spore=random terrain, npc.