Sonic Generations was a seemingly celebratory attempt to reconcile Sonic's troubled 3D incarnations with the 2D glory days of the Mega Drive era. It didn't entirely work, but, for better or worse, it's probably one of the best Sonic platformers of recent years.
Viking: Battle for Asgard is an entertaining third-person brawler. It's a bit naff, and has atrocious stealth sections, but also lets you thwack hundreds of enemies with axes and stuff. Sometimes that's all you need from a game, and that's okay.
Both bonus games are available for those who pay more than the average. It's a strange, eclectic bundle, but there's some good stuff in there. For $3.80 or above, you can get a collection of Dreamcast Games, a Sonic kart racer, Total War: Rome 2 DLC, Football Manager 2015 DLC, Empire: Total War, standalone Company of Heroes 2 multiplayer DLC, a Sonic platformer and a Viking brawler. There's also Shogun 2's standalone expansion available for those who part with $12 or above.