Now who's the idiot?
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They both wind up in Heaven's Gate.
And if there was no connection between the games but the fact that they take place in the same world (which I've been telling you morons for
how damn long now?), Sting would likely not have bothered pointing it out to us that they are connected.
Also, a great many RPGs use the World Tree as a thematic element, and rarely is it actually in the very center of the world.
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It certainly wasn't in Riviera; the World Tree that appears on the floating islands is in Elendia, which is very much not in the center of the island. And in Yggdra Union (i.e., on the surface world) it's in Marduk, which is also not near the center.
Name for me ten games where the World Tree is actually dead center in the middle of the map and then we'll talk.
You need to pay more attention to these games when you play them. Either that, or you're all permanently braindead and there's no cure for you.