In a previous post, we mentioned we'd make a step-by-step tutorial on how to create High Poly rock-models, similar to what we'll use for our game, so let's start!

Before anything, we get some reference for the rock we want to create, let it be a cliff-like, or whatever you like. You'll always have to check your reference so you can copy the details!

This is how the rock will look at the end -

Without further ado, let's begin -
So we start by creating a square primitive in ZBrush, and modify it to our liking, to make a base mesh for our rock.

We can also change the material, since that red wax won't help so much - what about some rock-like-mat?

Now you need to use the TrimSmoothBorder brush, that is located in the lightbox-brushes-trim section. Double click to use it as a brush, and then add a square alpha to it (alpha 28), and leave it on freehand. Also, uncheck SMT (smooth) for subdivisions, we don't need that.

Next, this is a personal preference, but when it comes to rocks, I like to up the subdivs a bit. Reason is, that trim brush does a good work detailing while "destroying" the model, so while it gets the work done in low subdivs, it creates a different look on high sub (lets say, around 200k points) . Now, to continue, see all those hard edges(highlighted in green)? lets trim them down

Now my model sits around 200K polys, and has its edges trimmed. Perhaps, by this point, you're already annoyed by the square trail that the alpha leaves, but we'll take care of that later. don't smooth it! it'll help us to create more detail for our rock.
Also note that lighting can help us a lot to notice details, and check if we did a good job while trimming the edges! so play around with it (get dramatic if you want)

Something I should've mentioned before, if you use a movie timeline while you model, it'll help you tons! let me show you if you didn't know about it.

Go under Movie tab, then Timeline, and click on "show"
Now, if you press on that timeline (the bottom part), you'll create a "savepoint" for the camera
Try creating one savepoint, then moving the camera around, and creating a second one. now with the orange square, move between them.

With that, you can lock many camera views so you can sculpt the main sides of the rock without having to go back and searching for a good angle again.

Another important thing. Perhaps the most important while sculpting your rock-
Directionality. Your stroke's directionality. While you use that trim smooth borders, try that your brush strokes all go in the same direction - take mine for example, they were all oriented like this :

Let's continue. After getting those edges done, we should take care of the main parts of the rock. Lets say, its the top one in this case. For this one, I'd like it to have big, clean faces, so I'll use a bigger brush size.

Looks blobby, right? we'll take care of that in a bit. let's go back to the first side we were sculpting, and add more faces, and shapes.
Now, with this brush, we get the chance to create cool shapes if we hold the alt key (so we use the ADD function, instead of the SUB)

Lets try sculpting with some add-brush strokes (hold alt) and then overlap them with some of the normal strokes (sub) to create a cool effect.

Depending on how you've been modeling your rock, perhaps it is time you consider some dynamesh (keep an eye on the resolution, you wouldn't want less geometry, or TOO much)

This is how it's looking so far, after forming some secondary shapes on the rock.

Alright, so, after the dynamesh, lets up the subd's. 900k or so is okay.
We'll proceed to refine some details in the rock, to make the faces sharper, and erasing the annoying square alpha's leftovers.

Here's some contrast between some mild- polished faces, in comparison to some that aren't.
To erase the square alpha's leftovers, lets use polish, or H polish, depending on your preference (check both, and also play with the brush modifier) do not smooth anything, just polish it like your life depends on it.

After some refining, it looks like this. now lets try to break those edges a little bit.
Go for smooth borders again, and this time apply more pressure (small brush)

What about some cracks, or some places where the rock was broken, or hit? lets try this.

Dam standard, and create any shape you want.

After that, we apply trim smooth borders on..the borders.
Once that's done, we start bashing the crack with soft-pressure- trim smooth borders and h polish.

And we're done! we could slap some alphas, add many more things, but its good enough for a rock that took us one hour to make.

Here's the same rock with just some noise.