According to the current state of research, the aspect of exercising power, dominance and control over what is happening in the game can be seen as the central determinant of the fascination of computer games.
This is a topic I've come to think about quite a bit before: what psychological aspect makes us feel comfortable playing something that takes hours and hours to only make a little progress? I'm more of a believer in the feeling of satisfaction for having reached achievements or goals that require hours of play.
At least I haven't had to fight a dragon in my garden so far...
Still no dragons where you live? Here I've already fought Cyclops that enter my apartment without permission :P