Help with creating a self-study curriculum for game art?

Anatomy

One thing I don't see any of on here is anatomy. If you ever want to draw or sculpt people or creatures, you're going to need a lot of anatomy.

Faces
   - Do each facial feature from several different angles. Eyes, noses, lips, ears.
   - Rough head forms, different angles.
   - Self-portraits. (Can use two mirrors to get other angles.)

Body
Go through the body piece by piece, covering one joint or body part at a time.

   - Draw the bones - each from multiple angles.
   - Draw the muscles - one at a time over the bones - multiple angles.
   - Draw muscles - layer together over the bones - multiple angles.

Get your hands on George Bridgman books. His drawings are a bit sloppy, but good training in the forms of the figure.

Gottfried Bammes anatomy books are pretty much the best, though they have a lot of extra "fluff" between the good bits.

Form

It looks like DrawABox has pretty good stuff for this, but here are my suggestions for a progression of exercises:

Start with flat planes.
   - Draw rectangular planes from different angles. Draw lots of them.

Divide up your planes.
   - Draw both diagonals on the plane to find the center. Then you can divide it in half in both directions.
   - Look up the diagrams to divide a rectangle into any number of equal parts - thirds, quarters, fifths. These will work on any rectangle in any perspective. Practice them.

Draw circles on your planes.
   - Look up "draw circle in perspective" and you will find diagrams on how to find points on the circle inside a rectangle. There is one that is accurate but also quite a bit of work, and also a more rough estimation method. Learn both.
   - Practice drawing ellipses freehand - different widths of ellipses.
   - Practice drawing ellipses on square planes more, and more.

Draw basic forms.
   - Cubes, spheres, cylinders, cones, pyramids, toruses. - all different angles.
   - Start with cubes/boxes - draw lots of them.
      (Each of the other forms can be fit inside a box.)
   - Draw each form 20 times from different angles?
   - Also draw them with different proportions. Long and thin, short and fat, etc.

Combined/Truncated forms.
Take basic forms, add them together and cut pieces out of them.

   - Take a cube or rectangular solid. Divide it into at least thirds, and make a set of steps out of it.
   - Draw another set of steps, then cut it the other way to make a Qbert arena out of it.
   - Take a box and cut an archway into it (cut out half a cylinder and a box).
   - Cut up angular slices out of a sphere, like an orange.
   - Cut a 1/8 piece out of a sphere.
   - Cut flat slices off of a sphere.
   - Cut a cylinder on an angle (draw a box, add the cylinder inside it, draw the cutting plane, then draw the ellipse(s) on that).
   - Draw a cube or box, then add a cylinder to one side of it (or more).
   - Draw a cube with half of a sphere on one side of it.
   - Draw a cube, then bevel the edges of it.
   - And so on. Come up with your own combinations/cuts.

Combined/Truncated Forms - From Life.
Find some simple household objects: batteries, pencils, books, calculators, cups, cans, etc.

   - Ignore the details and draw the object out of basic forms. Look at the real object and construct it from different angles.

Complex Combined/Truncated Forms - From Life.
Find some more complicated objects to draw: tools, utensils, devices, furniture, power plugs, light switches, bottles, etc.

   - Draw them from a few different angles. No freehand outline drawing - contruct them. Build them up / cut them out of simple forms. Try starting with a bounding box and cutting the shape out.

Rendering

Once you have an idea how to draw basic forms you can learn how to render them with light and shadow. Start with a sphere. Set it up with basic 45-degree lighting (up and to the side). You can either find or make basic forms in real life (paint them white) and set them up with a light, or use Blender to make renderings of them to look at.

   - Draw the sphere with a full range of values. Do this at least 3 times.
   Do not use any outlines! Just draw in a circle very lightly to start with.
   Make sure to capture the gradation of value on the light side of the sphere, the core of the shadow, the reflected light, and the cast shadow. There should be a clear difference between the lit and shaded sides of the sphere, but since there are no hard edges on a sphere, there should be no hard edges on the shading. Also shade the background, it should be a medium value—lighter than the dark side of the sphere and darker than the light side. (this can take some patience with traditional media.)

   - Now try rendering a few cubes.
   Use similar lighting, but make sure that each of the three sides of the cube that you can see have distinctly different values.
   A cube should be pretty easy compared to a sphere. Each side will be mostly a uniform value, except for a bit of reflected light. Fully render the background, cast shadow, etc.

   - Keep going with the other basic forms.
   - Try different lighting and view angles with each form.

   - Render combined/truncated forms - copy some of your drawings of complex forms and try to render them.
   - Don't forget cast shadows!

If you can draw and render basic forms, and you can simplify complex forms into their basic forms, then you should be able to do pretty much anything.

Reflected Light

Reflected light is a big deal. It can make all the difference between a flat, amateurish drawing, and a drawing that looks beautiful and real.

Any surface that is hit by light becomes a light source.

This is what you have to remember. Every surface is a potential source of reflected light.

Don't forget though, if there are no nearby lit surfaces, there will be no reflected light! If you have a ball floating alone in a void, lit by a distant sun, there is no nearby surface to reflect light, so the shadow side of the ball will be completely black. You basically never have no reflected light in real life, but it's important to remember that you can easily have less reflected light than there was in the ideal sphere rendering you did before.

More often, you forget to add reflected light where there should be some. With complex forms, each little face can reflect light onto others. To render accurately, you need to do it step-by-step. First, forget about reflected light and cast shadows. Block in the shadow sides of the forms. Any plane that faces away from the light is dark; planes that face towards the light are more or less bright. Then add in the cast shadows. Now you can see which faces are still lit and can therefore add reflected light. Go face-by-face and imagine if that face was gently glowing, how would it illuminate the forms around it? Because it's a relatively broad area that's emitting (bouncing) light, the reflected light will be soft, no hard shadows.

Observation vs. Construction
(Drawing what you see vs "constructing" things from imagination.)

Don't exclusively do one or the other. Alternate between them.

Lots of people these days just copy photos and still lifes all day long. Their work ends up looking amazing, but they can't draw from their imagination to save their lives, and they have no concept of form. Ask them to draw something they can't see and don't have a picture of, and they are helpless.

There are also people who only draw from imagination, never what they see. They -may- have a good feel for form, but still tend to end up drawing the same thing over and over. They don't see the variety of real life, they don't see how their drawings are totally divorced from reality, and generally are weak with lighting, atmosphere, and environments.

In general, don't focus on one thing for too long. Keep changing, focusing on your weaknesses. This sounds like a stupid warning, but it's an easy trap to fall into. If you practice one thing, you will hopefully get good at it! Yay! But if you do this too long, whenever you try something a bit different, you will really suck at it in comparison! Especially if you are posting on social media, this will kill your motivation to fix your weak points and become a better artist. You'll stick to the one thing you are already good at and will stop learning.

Measuring

When drawing from observation (still lifes, self-portraits, figure drawing, etc.), learn to measure. You know, the old-school way: Hold out your pencil at arm's length, close one eye, etc. You can find tutorials about it online. Not only is it a very practical way of making accurate drawings, but it's very good training for seeing distances, proportions, etc. It won't feel like it, this method is much faster and less painful than the alternative. Think of it like learning the piano. You don't learn to play the piano by banging around until you find the right notes by sheer luck. You take as much time as you need to figure out the right notes first, then slowly get faster at it. It's the same with art. If you start slowly and accurately, you will soon get faster with the same accuracy, but if you scribble around quickly, just hoping to get something right, you are wasting half your time practicing bad drawing, and it will take a lot longer to become skillful.