I just had a randomly spawned idea by reading this thread. Since I don't have time to make it, maybe sharing it will inspire someone.
I read the post about godzilla attacking the city. This would be an awesome concept to build a city-building game around.
The whole theme would be you are building a city in a world where giant monster attacks are a naturally occurring thing. It would be basic SimCity except you can build defensive structures and some basic military outposts or units. The military outposts/defensive points would be fairly expensive, so you'd have to have a smoothly running city to be able to afford enough to defend the city.
You could go off on a tangent with various monster-attack related structures. Shelters would prevent deaths when the monster is rampaging. Sirens to sound alerts of incoming attacks, which will let shelters fill faster. Refuge centers for when homes inevitably get smashed to pieces.
Your growing city would have a built-in conflict. Your recent expansions need to be defended. The larger your city, the larger the rampaging monsters or more frequent. You could even link pollution to the type or number of monsters - as it seems to be a common theme with giant monsters.
And following the similar SimCity theme - you wouldn't directly control anything. You just designate the build area. If you've got an fighter base, they just attack the closest monster. If you've got a tank base, they'll pathfind to the closest monster via the roads you built.
If someone made this game, I'd kickstart it. Even if (or maybe especially if) the graphics were original Sim-City quality.
This does actually sound awesome. It's like some kind of Tower defense meets simcity...