Plot Twist discovered 25 years later
Probably nobody cares, but listen up!
The Chrono Trigger present-day & middle ages characters (Crono, Lucca, Marle, Glenn [or "Frog"] and Magus) along with some previous NPCs (Fritz, Gaspar, Norstein Bekkler) are all playable in this but are in disguise. (Perhaps others, too) They are very integral to understanding and appreciating the convoluted nonsense of a plot. Since the designers didn't do a well enough job to convey this, most players just throw up their arms and say it's ridiculous and unfaithful to the spirit of the original.
I would mention Schala, too, but we all know by now that Kid/Harle are partial clones. That, and Belthasar, are explicitly revealed.
If you're interested to know how I discovered all this, then send a DM. I don't want to spoil it too much, because figuring it out was half the fun. Just know that out of the 45 playable characters, there are some you may have recruited and used and were none the wiser about their importance as, shall we say, puppet-masters. The keys are in the Status screens, checking Origins, spending as much time as possible at Viper Manor, and paying very close attention to what the Chrono Trigger-game designers were trying to convey about their characters in measly 16-bit pixelated graphics of the first game. It's not ideal, but try to see them as fully-fleshed out people who will eventually transition to adults.
Pip and Marcy are playable characters that are used as clues.
Also, do not bring Norris into the Dead Sea.
That is all.
"All life begins with Nu and ends with Nu."