I agree. Tennis games are usually excellent, especially when playing locally against a friend. It's a simple, tried and true concept (Pong) that can really lead for some intense, heated moments. Even playing against a PC can become completely absorbing.
But SEGA Superstars Tennis on the Wii is especially cool - you wouldn't believe how much motion controls can add to a game like this, and they play excellently.
Oh, and check out the roster!
*spoilers in pic*
It's absolutely beautiful! Each character also gets their own special power move that they build up towards by playing well, similar to Mario Power Tennis, yet with surprisingly less tiresome animations.
Then you've got the themed courts (CURIEN MANSION!!!!), and a whole bunch of SEGA-themed missions/mini-games (*cough* even Puyo Puyo/Space Harrier *cough*) that you play where you turn the Wiimote sideways like an NES/SMS controller to unlock characters/alternative music/new courts/missions/etc.
It's just so cool man.
Oh yeah, and I've been playing around in Billy Hatcher, which is a lot more fun than I remember it being! lol
