Plunk. Plunk. Overoveroverover plunk. Tetris, developed by Russian programmer Alexey Pajitnov in a three-week coding frenzy, is a blissfully simple game: arrange the falling shapes ("tetraminos") to form solid rows of blocks. Since its introduction, Tetris has become perhaps the world's most imitated computer game, with versions available for every platform from the Mac to the PC to the Palm. Even better, tests show that it re-formats players' brain waves, thus porting itself directly from the computer to your personal wetware. Pleasant dreams...

Angela Gunn