The lights are on
Is this a problem because you are too young to play "M" rated games? I too had to deal with that when I was younger, so I can certainly understand why you are frustrated. Might I suggest purchasing a Ninetendo console if you already haven't? Nintendo has plenty of games rated "T" or under and could easily satisfy your desire to play games in the meantime.
As for your Watch Dogs example, I don't think the reason why it is rated "M" is because of fowl (a pun in response to your avatar) language. Watch Dogs appears to contain violence not suited for all audiences. It might also touch on mature topics, potentially terrorism, which ESRB would not approve a "T" rating for.