To be honest, I only ever played the Sonic the Hedgehog games mostly from Sega. Sega is still around making games even this year. I’ve never really checked out many of their other games though. Here is a link to the Sega website:
This link is about the different types of consoles made by Sega. I do remember something about the Sega Dreamcast console from when I was younger though.
This link is about the top games from over the years of Sega’s reign.