Mario Tennis Open is the newest Mario tennis title from the Japanese game developer, Camelot. It lets you play as any one of the gang of Mario characters, and they each have specific strengths and weaknesses. If you'd prefer something more personalised, players can also use their 3DS Mii character.
Mario Tennis Open comes equipped with the game modes you would expect from the 3DS: singleplayer, local multiplayer, online multiplayer, and "Street Pass", which lets you engage in games with other Miis that you might encounter as you're wandering around with your 3DS. While I wasn't able to make use of the multiplayer options, which allow you to play against other 3DS-toting friends (only one of whom needs to own the game), there are still a bundle of options for those going solo.
First up is the tournament mode, where you play against a range of opponents in order to climb the ranks and win tournament cups. Getting through one tournament subsequently unlocks the next; there are four different tournaments that you can play through.
Exhibition mode lets you play against different characters on different courts, either in a singles or doubles game. Here you can choose your opponent, the skill level of the game, the court, and the number of sets and games you'll play, as well as the starting positions of each player.
The gameplay in these two game modes is pretty straightforward: manoeuvre your Mii to the right spot on the court, and then choose from a variety of different shots (helpfully referenced in the lower screen while you play). You can go for a lob, drop shot, slice, apply topspin to your shot, or hit it flat and hard. For players finding all the options a bit much, the x button will perform a 'simple shot', but of course you won't want to run around pressing just one button to hit the ball for long.