Looking back at the phenomenal success of the most popular casual computer game 'Tetris' - on its 25th anniversary on June 6 - the game's creator, Alexey Pajitnov, said at the E3 Expo in Los Angeles that Tetris had largely been both addictive as well as entertaining!

Tetris has successfully rolled past the 25-year milestone due to the inherent simplicity of its content and interface, and its typically intuitive gameplay - even those with near-negligible gaming experience can easily play this game.

Referring to his momentous game, the nostalgic Pajitnov said: "The program wasn't complicated. There was no scoring, no levels. But I started playing and I couldn't stop!"

Over the years, there has been unending duplication and evolution of the basic Tetris format - that of rotation of falling geometric shapes on a rectangular playfield; and completion of horizontal rows of blocks!

Tetris, which was initially released as an IBM computer game, went on to become a worldwide sensation once it came out on Nintendo's Game Boy system in 1989. As per the Tetris Co. statistics, over 35 million copies have thus far been sold of the Game Boy version of Tetris.

However, it was not until 1996 that Pajitnov started receiving royalties from the sales of Tetris - the game that he created as a diversion from his work at Russia's Computing Center of the Soviet Academy of Sciences!