A rather in-depth simulation, with the apparent goal of keeping it real, to the point that you can't save the world.
If you get frustrated easily, this isn't the game for you. You'll rarely make it anywhere near to saving the world, much less saving it at all. The game is realistic to the point that it is almost impossible to save the world - and not in a fun way like Pandemic. Every game more or less starts the same way, and very little of it seems to be randomized, so if you win it once, there's not much replay value.