Mario Kart 8 was Second-Best Selling Game in May

Well, it's official. Mario Kart 8 was the second-best selling video game in the U.S. in May, despite being on sale for only two days that month.

The kart racer was only outsold by Watch_Dogs, a multiplatform game released for five systems, including PC.

It will be interesting to see how Mario Kart 8 will continue to sell. Many Nintendo titles have the unique luxury of being 'evergreen', meaning they continue to sell long after release. Case in point, you can still buy Mario Kart DS in stores, despite the game coming out nine years ago, and with two more recent Mario Karts released since.

My guess: Mario Kart will eventually be one of the top two best-selling Wii U games of all time, right up there with Super Smash Bros. for Wii U.

I'll be more curious to see June sales, after the game has been out for a while. Should be interesting!