Cellery-A computer virus lets you play Tetris

The Cellery worm, which gets its name from a message it displays saying 'Chancellery', makes changes to Windows settings to ensure that it automatically runs when the operating system starts up.

While the Tetris-like arcade game is running, the worm plays a MIDI music tune, and searches for other network drives and attached computers to also try and infect.

"This worm puts up the Tetris game as a smokescreen while it tries to hop from computer to computer across your network," said Graham Cluley, senior technology consultant for Sophos.