You get access to multiple LEGO bricks and you can use them to make your own creations on Google Maps.
You get access to the entire territory of Australia and New Zealand to showcase your creation.
Google spoke about this project:
Created downunder and exclusive to Australia and New Zealand, Build is our latest Chrome Experiment and uses the latest in browser technology in Chrome. So start building at buildwithchrome.com and don’t forget to share your creations with us on the +Google Australia page and we’ll reshare the most original ones!