I'm not sure exactly what counts as retro but my probably longest/oldest favorites are Pokemon and Sailor Moon. My first game system of any kind was the gameboy color, I had the green one, and my first game was pokemon crystal. I think I was in the 4th grade or so? And I had an older friend that got me into sailor moon when I was in 2nd grade and we would play pretend as the senshi whenever we would hang out. I flip flopped for a while between mars and mercury until we got another friend who had shorter hair and forged her to be mercury hehe.