Are We Living In A Computer Game?

There is a theory that says everything we can see, including us, exist only in a fabricated world as if we are living in a huge game of Civilisation.
This isn't a new theory, the philosopher Rene Descartes pondered way back in the early 17th century if we were 'just a brain in a vat which thinks its living in the real world'?  
The director of the Centre for Evolutionary Computation and Automated Design at NASA's Jet Propulsion Laboratory recently picked up the Descartes thread and said that the growing power of computers means it is possible that in the future humans can create their own universes and simulations, and that we in turn could be living inside a simulation right now.
So what if we were living inside a video game, the whole point of a video game is to score as many points as possible by the end so accepting the principle that this is just a massive game of Grand Theft Auto, somewhere we are racking up points or losing points for our actions and at the end of the game, or our death, we will be presented with a breakdown of the score of our 'life'.
The problem is we don't know what we do to score or lose points so we don't know how well or bad we are doing as the game goes along. Perhaps we get points for something as seemingly trivial as opening a door or lose them for clapping our hands.
If we wrote the programme we would more than likely reward good manners, honesty, kindness and generosity and penalise the attributes such as selfishness, jealousy, greed and intolerance but as we didn't write the programme and it might not be humans, it could well be another race completely which views entirely different attributes as point worthy, it may be generosity that is frowned upon and showing compassion halves your point tally.
As with all computer games, there must be glitches, easter eggs, errant code, bonus's and the unlocking of new 'levels' but my brain hasn't got enough computing power to consider all that so instead i'm going to spend the next 30 minutes opening and closing doors because you just never know.