This is a really neat concept, and its cool seeing the cities expand outwards and slowly creep towards inactive cities.
Unfortunately, I ran into the rare mouseclick bug every time I restarted, so I never got more than 4 cities.
I also wish there was even just a sound effect for starting and ending the mouse drag, but it happens when you run out of time to properly finish the game.
The art for the kaiju is also nice, and the animation for firing its laser beam is well done.
Despite not being quite all there, this is a neat base for a more polished execution.
Good work!