I've been playing Quinn for years and it has been being actively developed and supported throughout this time.

An excellent web-based tracking system (linked in the application) has been developed that allows players to easily find servers where they can join and compete against a number of opponents. With the newest version (3.4) there is also online highscore tracking, with many unique features that are a lot of fun to check out if you're a typical tetris-geek who likes looking at statistics. High scores are tracked, as well as high lpm (lines per minute). Also, the scores show averages for individual players and averages of all players in a country.

Game-play is the best I've seen for OS X, and I've been playing Tetris since it came out for NES so I'm picky about this stuff. The pieces rotate and drop just as expected. Graphics and animation are pleasant as well.

There are a couple minor graphic glitches (that don't effect game-play) in 3.4 that the developer is aware of. They will be fixed with a minor update very soon. You can read about the game development progress on the Quinn forum at the developer's website.