TetriNET

TetriNET is a multiplayer online "Tetris" game for up to six people, that supports team play.
History.
Tetrinet was originally developed by St0rmCat in 1997.
The last official version is 1.13. The game was originally developed for Windows and was later ported to other systems.
St0rmCat released "TetriNET 2" in 2000, which features improved graphics, more types of special blocks, additional features (such as hold piece and block shadows), and a master server.
Gameplay.
TetriNET plays like standard multiplayer Tetris but with a twist: clearing rows will cause special blocks to appear in the player's field. If a line containing a special block is cleared, then that special block is added to the player's inventory. Clearing multiple lines at once increases the number of special blocks received.
At any point, a player may use the special block at the beginning of their inventory on one of the six fields (either their own or an opponent's). The effect depends on the type of special block:
The last player still able to place pieces in their field is the winner.
Depending on the server used, some alternative rules may be available.
Music.
The classic TetriNET download came with a single MIDI file that plays during game. This music is known as "The Dance of the Spheres" and its authorship is claimed by David Lilja, though other sources list the author as Davie M Karlsson.
Variants.
In addition to the rules implemented by the standard TetriNET 1.13 client, there are a number of variants available.
TetriFast.
TetriFast removes the one second delay between pieces found in the standard TetriNET gameplay. As the piece delay is implemented client side, a trivial modification was made to the network protocol to prevent TetriFast clients connecting to standard TetriNET games.
TetriNET/TetriFast 1.14.
The 1.14 protocol is another variant, where every player will receive the same sequence of pieces.
Blocktrix.
Blocktrix is an alternative TetriNET client for Windows. In addition to supporting traditional TetriNET and TetriFast protocols, it has a newer Blocktrix mode that includes a number of additional special block types:
TetriNET2.
"TetriNET2" is a multiplayer "Tetris" game by the original creator of "TetriNET". In addition to the special blocks found in the original TetriNET, it has five new ones:
In late 2007, like other clones, TetriNET2 was shut down per the request of The Tetris Company. The TetriNET2 website and servers became unavailable for several years. As of early 2010, TetriNET2 is back up and running (per request of many fans that are not satisfied with the lack of game development by The Tetris Company). The TetriNET2 website and servers have been recovered, relocated, and restored.
Popularity and reception.
With clients for various platforms available, the game was also well received in the Linux community. The Linux conference linux.conf.au even included a programming contest where contestants tried to program TetriNET playing bots, who could connect to the game server and play the game. The prize for the best bot was a A$40,000 IBM pSeries server. The game was also played in LAN parties. Game Revolution named Tetrinet as affordable alternative to Tetris.
In a 1999 review of The Next Tetris, Game Revolution named TetriNet as "truer to its Tetris roots" and "If you want multi-player Tetris, the network based Tetrinet is much more fun.".