It is you versus the world/galaxy/universe.  You have to use what you have been given to build an army and find victory.  The strategy game is another excellent genre to exercise the mind, and a true time sink if it is a good game.  Our nominees this year are:

Warhammer 40,000: Dawn Of War II - Retribution
Orcs Must Die
Kingdom Rush
Frozen Synapse

I am going to be honest here.  I did not play any strategy games that game out this year.  In fact in our entire group the only person that did was Rampage.  As such he got to choose the winner on this, and the game he choose was Warhammer 40,000: Dawn Of War II - Retribution.