You said "young" So, unless it was a PC game, most people will be naming Xbox 360 / PS3 games, which was just last generation. I'm 25 and grew up on Nes playing Mario, whee of fortune, duck hunt <3, meteoid. Then sega genesis with games like Aladdin, lion king, home alone 2, sonic series, streets of rage, battle toads Etc It'd be a decade before any system could have online play