The Developers' Room was, without a doubt one of the most interesting endings, but necessarily conclusive.
It was hilarious to hear what shenanigans the developers' had to say, though.
I only found out about the 10 multiple endings, let alone New Game +, through the strategy guide. I never would've imagined the game multiple endings if I didn't have a strategy guide telling me that.
While Nintendo Power, back in the day, said the game would have multiple endings, it also said that the game was designed in a new way that did away with dungeons. It's like, how can an RPG NOT have dungeons? After that statement was disproved, for when I first played Chrono Trigger, found out that it actually had dungeons, decided that the multiple ending claim was bunk, too.
...
Anyways, I've heard rumors that Chrono Trigger has 22 endings, 3 of which regard Magus and haven't been stated amongst the commonly known 10 endings.
If I recall, the guide only covers "The Top 10 Best Endings of Chrono Trigger." This implies that there are more than 10 endings, even if out friend from the developer room only tells us that there are 10 endings.