Compared to Nintendo’s other first party developed platfomers for Wii, Donkey Kong Country Returns is probably the most challenging. And that’s what Retro Studios wanted.
"I thought it was extremely important that the game [Donkey Kong Country Returns] be challenging. When this project began, I played the Super NES version again and was a little irked at how hard it was," Mike Wikan, Senior Designer at Retro Studios, said in an Iwata Asks interview.
"I thought it’s really important to make the game tough, but in a good way. I wanted to make a game that was not simply difficult, but possessed a kind of difficulty that made players want to try it again. To be more concrete, when there’s a place where you have to jump, I thought it was important that, rather than make players angry, the game makes players feel that even if they fail, they will be able to jump better next time."
"It’s important to make it so that when players mess up, their frustration causes them to want to improve their playing," Satoru Iwata, President of Nintendo replied. Earlier he mentioned how tough the mine cart levels were in the original Donkey Kong Country.
Another interesting tidbit from the interview is about Donkey Kong’s new breathing ability. That idea was an order from Shigeru Miyamoto who also told the development team to not to change the game’s music.