Mario Kart DS is a great game that any gamer would love to play, especially with the addition of wi-fi.
In MKDS, there are many more modes than in previous renditions of the series. In Singe Player, you can race in a Grand Prix, Time Trials, VS mode, Battle mode, or go through various missions. In Grand Prix mode, there are 2 different Grand Prix's to choose from (Nitro Grand Prix and Retro Grand Prix). Each consists of four cups, which in turn consist of four tracks. All in all you've got 32 tracks in total, and 8 different cups to race in. In each cup, you get a certain number of points depending on where you place. If you're in the top 3 point-wise at the end of the four courses, you'll get a trophy. Plus, when you get gold trophies sometimes you unlock new characters and karts. This is the "main mode" of the game so to speak, and is pretty fun until you finish it. After that, you'll find some of the other modes appealing to you more.
In the Time Trials mode, you can choose from any of the courses to race through. The twist is, you're racing by yourself. The game will save your previous best times on each track so that each time you can try to beat your previous best. Not only that, but rather than making you figure out how your doing compared to your last best score, the game generates a ghost that replicates your best time. This helps to keep it fun, and makes it even better to beat your personal best.
VS mode is similar to Time Trials, in that you can choose from any of the courses to run through, but it also bears similarity to the Grand Prix mode since you can race 7 other drivers. There's also plenty of customization in this mode. You can choose the difficulty of your competitors, how courses will be chosen (random, in order, etc), how many wins you need (or races you need to play), and lastly if there will be teams. This mode is by far my personal favorite, since it adds a bunch of replay value and lets you play your favorite courses in any order you want.
In Battle mode, you can either have a balloon battle or a shine runners battle. In Balloon Battle, everyone has three balloons. If you hit them with any weapons (shells, bananas, or even run into them with mushrooms) they'll lose a balloon. Once you reach zero balloons, you're out, and the last kart still going wins. In Shine Runners, the game randomly drops shine sprites all over the level and you need to try and collect them. If you get hit - with the same weapons as mentioned previously - you loose a shine and it falls somewhere on the stage so that someone else can pick it up. While both modes have there ups and downs, neither really stand out as great or exceptional, just alright.
Mission mode is new to the Mario Kart series. In a nutshell, there are six different levels and 8 missions in each of the levels. Each mission has you do something small (like collect all the coins, hit something with a shell, drive through through gates, etc) to complete it. At the end of each level there's a boss which you have to defeat. There isn't much depth to the missions, or a really outstanding fun factor, they do add a little replay value to the game and give you one more thing to accomplish.
In total, there are 12 characters who each have three different karts. With the amount of karts (36 in total) and the different positives and negatives for each, chances are you won't get bored experimenting with each of them. Variety is the big thing here, and MKDS has oh-so-much of it. Also, when you start the game you get the option of choosing to create an emblem which goes on whatever kart you use. While you can't add much variety to the emblem because of the limited tools, it's still a nice little feature that adds some personalization to whatever kart you're using.
Even with all this in mind, quite possibly the best part of Mario Kart DS is multiplayer, and more specifically wi-fi. If you have a wireless internet connection in your house, you can go online and verse any other Mario Kart DS player in the world. In wi-fi, you play against 1-3 other opponents in four different races. Whoever has the most points at the end of the races wins. But it's not just come in first place or lose. If you're playing four people and come in first, you'll get three wins (for each of the three people you faced). If you come in second, you'll get 2 wins (the 3rd and 4th place people) and 1 loss (the 1st place person). Since disconnecting brings no loss if you're in last place, not having to come in first to get wins definately adds more motivation to just finish the races without DCing.
The Mario Kart franchise is a really successful one, which has had many top-of-the-line titles, including Mario Kart DS. A great single player mode that will have you playing for hours, a fun and fast paced wi-fi mode, and loads of variety and replay value which will keep you coming back. Mario Kart DS is a must have for any Nintendo DS (or DS Lite) owner.