I used to find King a reasonable challenge (I would not always win), but now something has changed. By about 1000BC some of the civs have armies of 12+ units, which if I was to try and replicate I would be totally bankrupt on maintenance costs. Now I just get routinely crushed, not a 'challenge' any more - just a frustrating impossibility. Have maintenance costs been drastically reduced for the AI along with production and happiness bonuses etc? Will have to go back down to Prince or else uninstall Civ5 - think I have about had enough now.