Mother is the brainchild of novelist Shigesato Itoi, a man who loves experimenting with video games and how they can work as a unique storytelling medium.
They're... hard to describe. There's three games in the series, and the main gameplay is similar to Dragon Quest (the original NES title is essentially Dragon Quest without random battles) but with its own twists, including a rolling HP bar in the latter games and rhythm-based combos in Mother 3.
They are also probably my favorite games of all time. Yes, I love them more than Zelda, more than Final Fantasy, more than Ogre Battle, more than Harvest Moon, more than God of War, more than anything.
They aren't games that can be gotten into expecting traditional JRPG values, because they don't have them. Their graphical styles are very simple, they are more humorous than dramatic (...usually), and they focus less on characterization and plot than they do on progressions of themes, typically having to do with family and growing up and loss. Outside of maybe ICO and Shadow of the Colossus, they're the most literary games I've ever seen.
I recommend you play them, if yyou can, though nowadays it's impossible to do so without emulation. If you want to talk more about options for playing the games send me a PM and we'll chat more about them there.
Wonderful, wonderful, wonderful games. Mother 3 may be my favorite game ever. I'm not sure.