I am a Rubyist that is just starting to dabble in Smalltalk and am trying to chose an implementation to experiment with. It seems like Squeak or Pharo would be a good choice, bu
There are a number of interesting possible starting points:
Explain more about what you want to achieve and we can help you better
Another choice to learn Smalltalk is Cuis.
From the description:
Cuis is different from other Squeak variants in that it takes an active attitude towards system complexity: As systems grow older, they usually become more complex. New features are added as layers on top of whatever is below, sometimes without really understanding it, and almost always without modifying it. ... The only way to avoid this is by understanding the complete system, and re-engineering the whole system all the time. Keeping it simple and consistent.
The code is on Github. The most recent image files are here.
Cuis has around 600 classes. This makes is very doable for a single person to understand everything. Later on you might want to switch to Squeak, Pharo or another Smalltalk as the vast majority of the classes and methods are compatible.