Once you've started the game, be sure to lower the game speed to the lowest setting. Then click Game Menu, Your see a list of options. Click on "Enter Code" then type in the code of your choosing. Then start building and speed up the simulation as wanted.

Effect	Code
Adds $1,000,000 to your money	dante
Everyone is happy	becca
Everything is upgradeable	bengan
Increased Workloads	kyrksten
Max Build Height	gustafsson
Reset the Simulation	reset