WebTV doesn't support Java and cannot download software, so that severely limits the choices. Also check out the Hot 50 WebTV Game Sites for another collection of WebTV-compatible games.
All games feature nice graphics and smooth gameplay.
No Java, no downloads. Tournaments and extensive message boards are part of this active community. Rather than pointing and clicking to make moves, you enter numbers corresponding to board positions. A simplified version of the game. Fun, but a bit annoying due to the constant popup messages after every move.