MOTHER (1989, Famicom): The series' debut, telling the story of Ninten as he works to uncover his family's connections to an impending alien invasion. Wasn't released outside Japan, but a prototypical English version, widely called "EarthBound Zero", was discovered in the late 1990s.
All three games feature an exploding robot enemy that can fully heal itself or its allies. In two variants. With one type appearing in The Very Definitely Final Dungeon.
Affectionate Parody: Of Dragon Quest, which is natural seeing as that is the game that inspired Itoi to dabble in game-writing. However, EarthBound's battle system drifts away from the DQ clone that is the original.
Book Ends: In the first MOTHER, a denizen of Magicant suggests you can never be happy unless they leave the house — but then, you leave yourself open to unhappiness, also. He concludes the best option is to do nothing. This becomes Porky's Ironic Hell in MOTHER 3.
Everything's Deader with Zombies: Zombie mooks pop up time to time. In MOTHER, you see them the early graveyard section of the game and Rosemary Manor. EarthBound's Threed has been completely overwhelmed by zombies, trapping them in a perpetual George Romero movie.
Genre Deconstruction: MOTHER is Itoi's meditation on what games are, why they are fun, and the logistics of applying JRPG logic to the real world. For example: Who designs dungeons? And why do people instinctively know to loot them? (Admittedly, the series' mythos got a little deeper with each game.)
Gotta Catch 'Em All: The Eight Melodies in MOTHER and EarthBound. In MOTHER 3, Lucas is in a race to stop all Seven Needles from being uprooted (or, when failure there becomes inevitable, make sure that he's the one that pulls them).
Hello, Insert Name Here: A prominent example, as this feature is used to name the game's most powerful attack and the food your mother gives you to eat every time you see her.
Not to mention the name of your dog, the friends that you will make along the path of your journey, and the um... "flavor" of the text boxes.
And you are able to give your own name as well as that of the main group. This can easily put the insanity of Giygas into perspective should you name yourself or Ness after him.
Our Time Travel Is Different: Ness' party travels to Giygas' lair, a cavern at the center of the Earth teeming with plant life, but it's otherwise empty. They deduce that Giygas is attacking from the distant past, and use Dr. Andonuts' phase distorter to send them there.
After disappearing at EarthBound's climax, Porky got lost in extensive time travel abuse, to the point where by the time of MOTHER 3 it's warped him to be an immortal old man with the mind of a child.
Sheathe Your Sword: A full-on assault on Giygas/The Masked Man is pointless. To win, you have to eschew violence (the antithesis of every JRPG at the time) and instead appeal to the humanity inside them.
Yin Yang Clash: Just As Ninten and Ness are all about the melody, the main antagonists of MOTHER accordingly have dissonant theme music. (Incidentally, this is the first hint that Porky is going to be trouble.) Giygas has no melody at all, only an incessant, high pitched ring.