I’ve been playing around with Unity 3D for a while, made a few nice demos with Rigidbodys, Physics, etc. Haven’t done anything with animations.
What do I need to learn to make a Mech game with walking animations, independent torso turning, etc? Mechanim? IK?
What I suggest you do is make a high-level list of what you want your game to do.
Then for each thing you wrote down, think a little lower about what will be involved in doing that thing.
For example, you need a mech. If you don’t find an asset providing this in the asset store, you’ll have to make the mech from scratch yourself. In other words, you need to learn how to make a character. This involves 3D modeling. So you’ll have to learn how to model.
Next, you said you don’t know how to animate. So I would look up how to animate models in Unity 3D.
You could start thinking about environments, whether you want this to go online, etc.
You’ll also definitely need to know how to code. And even once you’ve learned a language, you should look up good coding practices so that your code is extendable and closed to modification ( most important rule in my book ). The single responsibility principle is something helps with that.
So yeah, make a laundry list, and look into what’s involved in getting that laundry done!