This is hardly Nintendo's first foray into making Mario-themed sports titles. In the past, they've had huge successes with games like Mario Strikers, Mario Golf, and Mario Tennis. All of those are fantastic, fun sports games. They've proven that this concept, Wii family games starring Mario and friends as various athletes, is a concept that they understand how to do well.
It's unfortunate, then, that Mario Sports Mix is such a failure. There are four sports you can choose to play: Volleyball, Hockey, Basketball, and Dodgeball. Each of them can be played as a 2 vs. 2 matchup or as a 3 vs. 3 matchup, and all of them can be played with 1-4 human players, with the computer controlling the rest. You can choose to play as all the favorite Mario characters, and because the game was developed with Square Enix, some more characters, such as a Moogle, are unlockable. There are also various gimmicky courses with quirky obstacles you can play on, some of which are better than others.
Playing alone is a truly terrible experience. For instance, control doesn't even switch automatically to computer-controlled characters when they get the ball or puck, which is unacceptable in any sports game, no matter how simplified. Even if there's no one around, however, they offer online play to save you from ever having to play alone, but even playing with a group of people falls well short of the mark. The simplification of the sports in question has always been the strength of the Mario sports titles, but this one goes too far. Every single one of the games consists of passing and shooting/throwing/dodging, and that's about it, to the point that all four of them end up feeling relatively interchangeable, despite being very different sports.