TetriNET is a multiplayer online Tetris game for up to six people, developed by St0rmCat in 1997. 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 one of their special blocks on themselves or another player. The settings are also very customizeable. The percentage chance for receiving specific special blocks or even the 7 standard Tetris blocks can be altered for a very wide variety of custom game types. Source: Wikipedia & User Summary, "TetriNET", available under the CC-BY-SA License.