Break the strange beast egg while evolving your civilization trying to increase the damage done to the egg (and later to the monster which hatches out of it). Starting from the stone age and men with clubs doing very little damage and up to modern age fighting the egg with tanks, aircrafts etc.
The gameplay is fun, but the game doesn't progress when you're away, so it consumes a lot of your time. It doesn't seem to be finished as the reset basically doesn't give you anything useful, so once you reach modern age, that's basically it. Although technically the game is not over, there is nothing else left to upgrade or discover in the game.