textadventures.co.uk - Create, play and share text adventure games.
Math Games - Math Games is a website which kids in Preschool through 8th grade can practice math.
Ink by Inkle - ink is a popular open source scripting language for branching stories, designed for writers
DragonBox Algebra - DragonBox Algebra 5+ - The educational game that secretly teaches you algebra.
Mudlet - Mudlet is a freshly-minted MUD client, designed to take mudding to a new level.
GCompris - Educational Game for Children 2 to 10 years old.