There's a hidden room accessible by entering a trashcan located in the empty lot of Neo Tokyo, after defeating an enemy you'll be transported to an office where you can chat with a group of chickens hard at work programming. These fellows are actually Quintet, and they even explain that they are working on Illusion of Gaia 2 !
The literal translation of the title Tenchisôzô into English is something along the lines of "Creation of Heaven and Earth". Which is exactly the content that the game deals with.
Terranigma was the last main release for the Snes