This script that I wrote was made for animating characters without having to do rigging. It builds the bones and then when you hit the play button, the bones walk, so all you have to do is add the skin and possibly do some adjustments, and it will walk. The script is not 100% complete, as I have a lot of other stuff I am working on, but if you want to see it working, you can go to https://github.com/Skywola/anim and download it. After you download it, you can copy it into the text editor and run it, then go to the Animation view, press n to show the tab on the right side of the viewport, and select the create quadruped or bird button. (The biped and centaur do not work yet) . After it builds the character, you can click the walk or run buttons, also there is a speed setting under the character controls button. This was a project that I wrote originally for MAYA in MEL scripting language. It is pretty close to complete, but I just have a lot of other things that are higher priority at the moment . . . .