When I was living in Japan, I spent a lot of time shopping for video games in Den Den Town in Osaka (the equivalent of Hakihabara in Tokyo). At that time, I realized that I didn't miss anything special when I was living in Canada. Most of the games that never came out in North America are hentai games, quiz games, or crappy dating simulation games. Of course, there are some great gems (shmups, rpgs), but they are a minority and you really have to dig deep to find them.
Centre Court Tennis for the Nintendo 64 is one of those Japanese gems that nobody knows. I was only released in Japan and Europe. It's you typical tennis game with tournaments and stuff like that.
However, there's a different twist to it that makes the game much more interesting; you have to create your own character and entirely customize it from the legs to the head. As you progress through the game, you gain new accessories and clothes that you can equip to change the appearance of your character. It may sound silly, but it's really addictive. It's kinda like grinding in an RPG, but in a tennis game.
As for the graphics, they are the usual extremely low polygon blurry Nintendo 64 graphics. However, the typical colorful and cartoony Hudson style of that game is pretty nice.
There are many kinds of fields on which you can play, which keeps the gameplay fresh. For example, you can play on the top of a building, in a volcano, on ice with penguin walking around, etc. For each field, the referee looks different. That's a pretty nice touch.
This game may not be pure gold like some Treasure's games, but it's still a great game nonetheless. If you ever get the chance to get your hands on that game, you should definitely give it a try.