I started my first game and decided to be super aggressive. I attacked a player on sight after settling quickly won all the battles and started to siege the one and only city, the capital.  About 7 turns later I took the city. "Ive won!" I thought. "My gamble has paid off!" NOPE. I lost 3 turns later due to my war exhaustion. I had taken everything they owned! I had not lost a battle. War resolutions can be unintuitive and very frustrating mechanic. I dont mind a race against the clock mechanic like war exhaustion but at least give people a large debuff if they dont own anything! -4 war exhaustion is not enough.  Frankly I feel cheated.  Does anyone know how to cheat so I can get the city i conquered? 

If you occupy all cities of a player at the start of a turn, their war support instantly drops to 0 and you can force their surrender. You can then force them to concede some or all of their cities and, if they have no cities and no units remaining, they are eliminated from the game.