As the Go Sega website explains, this year marks the 60th anniversary of the founding of Nihon Goraku Bussan Co. Ltd., the company that became Sega five years later when they began importing coin-operated arcade games into Japan. To celebrate the occasion Sega is having a 60th birthday sale on Steam, which explains why the Sega games in your library may have new art. (It seems to have only rolled out to certain regions so far.)
If you were wondering why your copy of Sonic Mania had a Dreamcast spine, now you know. But why exactly are the Sega Genesis Classics now sporting Sega Saturn trade dress? Well, at least this explains why Sonic the Hedgehog 2 is available for free.
Among the games going cheap are Company of Heroes 2 for 95% off, Two Point Hospital for 70% off, Persona 4 Golden for 20% off, and Total War: Warhammer 2 for 66% off. You can also play that one for free this weekend. The sale runs until October 19.
Thanks to the success of Persona 4 Golden on PC, Sega have said they'll be porting more games our way in the future.