So the overall game name has always been Rotting and will remain like that forever, but the sub-title part which was "A Sonic Creepypasta" was added just to emphasize that this is a Sonic fangame (Which it still is). For a while it worked because Rotting's story was shorter and more structured like a creepypasta would be.

Recently though I've started to notice how much the story is evolving in my head and it's making me realize this is more than a short creepypasta now, it's a massive story to tell. So I updated some prologue lore which allowed "The Echoing Legend" to fit with the title, I considered "The Legend Of Rotting" for a while but stuff with "The Legend Of..." in the name is a little overused, so here we are now.

Like I said "Rotting" will remain as the overall name for the game as the entire story has the process of rot implemented in it somewhere.