Press the TILDE key to display the developer console. Type in the codes and press ENTER to activate them. Entering a correct cheat will close the developer window.

ineedcash           ->  Accrue $100,000,000
massdrop            ->  Big airport
doearthquake        ->  Causes earthquake
dotornado           ->  Causes tornado
setbudget   ->  Set budget to this value
setcash     ->  Set money to this value
hidegame            ->  Hides game
showgame            ->  Shows game