This is a tutorial teaching Inverse Kinematics in Gamemaker. While most tutorials either teach through video, or just a block of text with some code examples splattered around, this one differs. The tutorial comes as a Gamemaker project, meaning that if you test it, you'll have a fully working demo of inverse kinematics. This also means that you can mess around with the code to your heart's content. I believe that this is highly effective, as you do nor have to slow down reading in order to copy the code while reading. The tutorial is located in a script in the project, meaning that it comes with background-color highlighting and the whole pack. I believe different is better when trying to teach something, and this tutorial does definitely not lack in difference!
While the tutorial does not go very in-depth, it teaches the basics, and lays the grounds for further developement. This has been well recieved.