Civilization The Board Game, next version

Introduction
I deployed a new version of my computer implementation of  Civilization The Board Game. The implementation consists of three parts:

• Civilization Engine 
• Civilization Web Interface
• Demo. Demo version is deployed to Heroku, free quota. Please wait several minutes unless the dyno is brought back to life.

New features

• Buildings
• Improvements

Buildings

The player can buy building after researching appropriate technology.

Of course, the city should provide enough production.

Buying building is very simple. Click "Buy Building" button and city you want to enrich.

Last, but not least, point the square you want to industrialize and skyscraper is ready.

Replacement
But building new tower requires sometimes pulling down the old one. In order to avoid mistakes, a different button is displayed if a new building is supposed to be placed over the previous.
If new "star" building is ready to be set up, not only building on the same square could be removed but also another "star" construction.

Next step 
Wonders of the world.