Understanding Videogames

Quite useful Game Design course for beginners.

Gamification

Great teacher and some lectures that might be useful for game designers.

Model Thinking

Not exactly game design course, but an overview of different models from social/political sciences, economics, business, etc. Might be very useful if you design complex gameplay systems.

Design: Creation of Artifacts in Society

Industrial Design course but many principles are useful for game designers.

Interaction Design (specialization)

The new version of the Human-Computer Interaction course (unfortunately, the old version is no longer available). Specializations and certificates are paid on Coursera, but all the courses are available for free (just use search).

Game Theory

Game Theory is quite hard to apply to Game Design in a direct way, but some concepts (like Nash Equilibrium or min/max strategy) are useful to be familiar with. And there’s a good course about it.

Social Psychology

One of the most popular courses on Coursera, and quite useful for game designers.

Introduction to Marketing

A useful course for beginners. If you need to sell virtual items, it’s good to know how it works with other goods in the real world.

Leading Strategic Innovation in Organizations

Great course, if you want to learn how to “sell” your ideas to others, and what constraints you should overcome on the way.