Learney - Knowledge aggregator for developers

ANNO - ANNO is a city-building and economic simulation video game series, with real-time strategy elements.

Multiplication Kingdom - Learn the times tables by playing and having fun in the Multiplication Kingdom (for kids and adults!)

Tropico - Tropico is an Addictive, Strategy, Construction and Management, City Building, Sandbox and Single-player Simulation developed by PopTop Software.

Khan Academy - Khan Academy offers online tools to help students learn about a variety of important school subjects. Tools include videos, practice exercises, and materials for instructors. Read more about Khan Academy.

Stronghold - Stronghold Crusader is a RTS game from the series from Stronghold.