Tetris was created by Soviet software programmer Alexey Pajitnov in 1984. For a variety of platforms, it has been made available by a number of companies, most notably in the late 1980s during a court struggle over the ownership of the rights. Before Pajitnov and Henk Rogers co-founded the Tetris Company in 1996 to handle licensing, Nintendo released Tetris for a substantial period of time.
Tetris online requires players to move variously shaped pieces (tetrominoes), which fall onto the playing field, in order to create lines. The player can continue by filling in the empty spaces after the completed lines vanish and award them with points. When the uncleared lines reach the top of the playing field, the game is over. The more time the player can buy, the better their score will be. In multiplayer games, players must outlast their rivals; in some versions, players can impose penalties on rivals by successfully completing a sizable number of lines. A system for reserving pieces or three-dimensional displays are two examples of rule variations that are included in some versions.
