The main mode of the game, where you'll be able to uncover a vast amount of unlockable extras, is the Planet Superstars mode. The mode splits itself into various sections based upon classic Sega games, with Sonic the Hedgehog, Space Channel 5, Jet Set Radio, House of the Dead (aka Curien Mansion) and Samba De Amigo available from the start, and additional titles to unlock as you progress.
Each section starts off with a singles tournament, with victory in this unlocking a mini-game challenge. These in turn unlock further challenges, which get steadily more difficult as you move along. With Sonic, for example, you'll be challenged to collect rings that appear on the court, all the while avoiding spiked balls that are fired in your direction. Generally, each mini-game within a section is a variation on the same theme, with the challenge getting steeper and steeper as you move on.
There are sixteen characters from the Sega world to unlock, with the first eight available at the start, and the rest unlocked through Superstars mode. Naturally, old favourites like Sonic, Ulala, Tails and AiAi are available from the get-go, with the likes of Alex Kidd, Gillius Thunderhead and Shadow the Hedgehog uncovered through winning the tournaments.
Each character has their own strengths and weaknesses, and they also possess special moves that can be charged up and then activating by a good performance in a game. Sonic, for example, will become the yellow-skinned Super Sonic, whose shots are capable of completely changing direction without warning. It won't please tennis purists, but then neither would the presence of blue hedgehogs, flying foxes and maraca-waving chimps either.
When you can use the Wii controls, they're handled nicely, with slight swings of the remote needed to make the shots, while holding buttons allows for more advanced shots like lobs. The stick on the nunchuck controls movement and aim, although there is the option for motion controls with this add-on too. Admittedly, the swing controls aren't 1-1 in terms of how what you do is reflected on-screen, but that doesn't spoil the proceedings at all.
Ultimately though, as a Sega game, SST is a generally amusing affair, but as a tennis game, it comes across as a bit sub-par. Matches are short, with many Planet Superstars tournaments only needing two game wins for victory, and the multiplayer options are rather underwhelming as well. Okay, the single-player modes can last a Sega nut hours, but the less enthusiastic may well get bored fairly quickly. Sega Superstars Tennis tries hard, and has its moments, but like the aforementioned plucky Brit, it won't be winning any trophies any time soon.