Nintendo president Satoru Iwata has discussed third party success on Wii. It's possible, despite Nintendo dominating.
Nintendo consoles in recent years have been drowned in first and second party goodness, high quality games from the Japanese powerhouse that's caused problems for third parties trying to make a decent buck on the company's living-room boxes.
With the Wii it seems to be a different case, says Iwata:
Also, in the U.S., the third parties titles sold more on Nintendo hardware than on any other platforms for two consecutive months. Some had pointed out in the past that few third party software were successful on Nintendo platforms.As of the end of March 2008, there were only twelve titles for Wii by third parties whose global unit sales from the launches exceeded one million, and this figure excluded titles from Nintendo and Pokémon Company. However, this number jumped to thirty at the end of December 2008.
Likewise, at the end of March 2008, there were 28 third party DS titles which made the million-sellers list, but the number reached 49 titles at the end of December. As the hardware expand their installed bases, we are starting to see a cycle where more titles from the third parties are making the million sellers list.
The Wii's seen 30 million-sellers from third parties to date, alongside the DS with 49.