I've been playing a lot of Legend of Mana lately, my favorite JRPG on the PS1. In it, it has a system they call the 'Land Make' system. As you play through the games, you get artifacts. You can then place these artifacts on the World Map and they become new Towns, Dungeons or Fields. This allows a lot of replay-ability and gives the world a very open world vibe since, after placing the first two Artifacts, the order you get your artifacts is determined by the order you do your quests. I would like to do something like that in either VX Ace or MV, but I'm not sure how to go about it. For an idea of what I'm talking about, 0:40 to 0:48 of this video. This video also kinda shows what I'm talking about.