The publisher shared sales numbers for its major releases. Sonic Generations sold 1.63 million copies across four platforms (Wii, PS3, PC, and the 3DS Generations game). Mario & Sonic at the London 2012 Olympic Games outsold it with 2.39 million copies -- despite not being released in Japan yet, and only being on one platform at the time, the Wii. And, uh, despite being a Mario & Sonic Olympics minigame collection. Hatsune Miku Project Diva Extend for PSP (released in Japan only) was the other named hit, with 290,000 copies.
Looking up at Sega's sales by platform, it's worth noting that Sega's single PlayStation Vita release, Virtua Tennis 4 (called Power Smash 4 in Japan) sold just 10,000 copies between the Vita launch date of December 17 and the end of the year. That ... doesn't seem very good.