TetriNET is a multiplayer online Tetris game for up to six people, developed by St0rmCat in 1997 that supports team play. 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.
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: