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Squeak is open source version of Smalltalk and looks like a fun way to make games, edu apps and more… –

Squeak is a modern, open source full-featured implementation of the powerful Smalltalk programming language and environment. Squeak is highly-portable – even its virtual machine is written entirely in Smalltalk making it easy to debug, analyze, and change. Squeak is the vehicle for a wide range of projects from multimedia applications, educational platforms to commercial web application development.

Squeak: Squeak – [via] Link.