I describe the Moral Machine, an internet-based serious game exploring the many-dimensional ethical dilemmas faced by autonomous vehicles. The game enabled us to gather 40 million decisions from 3 million people in 200 countries/territories. I report the various preferences estimated from this data, and document interpersonal differences in the strength of these preferences. I also report cross-cultural ethical variation and uncover major clusters of countries exhibiting substantial differences along key moral preferences. These differences correlate with modern institutions, but also with deep cultural traits. I discuss how these three layers of preferences can help progress toward global, harmonious, and socially acceptable principles for machine ethics. Finally, I describe other follow up work that build on this project.