Recommended for individuals familiar with C#(Unity) or GML(GameMaker) but new to Ruby
Those engines rot your brain. Forget the concepts that the forced you to learn. Game development is so much simpler than what they make you do. Please, try your best to set aside the concepts those engines teach (we promise our approach to game development is much much easier).
Watch these videos to get familiar with the Ruby language and programming environment (they are ~20 min each so it'll be quick):
- Beginner Introduction to Ruby
- Intermediate Introduction to Ruby Syntax
- Intermediate Introduction to Arrays in Ruby
You may also want to try this free course provided at DragonRuby School
After you've watch the videos, you'll be ready for the Advanced Tutorial