What is the best electronic game

It is a matter of personal opinion.

The top 5 games of 2012 according to official statistics were:

1. Elder Scrolls V: Skyrim
2. Call Of Duty: Modern Warfare 3
3. Dishonoured
4. Borderlands 2
5. Tokyo Jungle

But the top-selling game of all time is an old classic, Tetris.
The best selling electronic board game of all time is "Operation".