Right so i'm making textures/sprite sheets for a simple project which is an isometric hack and slash rpg.
Writing the c++ is fine but the graphics I have no idea...
I want to know the method/software used to create graphics that look the same as seen in the existing game 'Diablo 1'. Here is a screen shot for reference. You can see I have sliced the image up with lines - for those that have made/worked with these types of games before you will understand it.
Thanks!!
Why on Earth would you want to? *wince at how ugly they are* Those poor artists, forced to work with such low resolution and small color palette... T_T
Err yeah, that was unhelpful. Lemme try that again...
After quadrupling the resolution, I think a modern method of rendering 3D models and trimming the renders into sprites would be more efficient than a historically accurate pixel art method. Especially if you were thinking of actually using the feature-lacking antique software they used then.
If you are talking about the idea of rotated tiles, that is called 'isometric'. By googling 'isometric tiles' you can find alot of details about it. 
Some people draw it by hand, some use 3D models and take screenshots of the model from various angles (Diablo 2 did that for the character sprites), and some just render in 3D and use a fixed camera angle (like Torchlight).
If you are wanting to know how to make art that is predominantly grey with very little color, in an attempt to make things look dark and gritty, and then covering half the screen in black shadows anyway, then first go learn about color theory before tossing it out the window. 
Probably the easiest way for most of that art is 3d pre-rendered sprites. This applies to the level art, and applies even more to anything that moves. 2d art with animation is kind of a pain as it is due to having to draw all the frames by hand, so imagine that in 8 or 16 directions like in these isometric styled games. This is where 3d plays in, just rotate the character 45 degrees and re-render.
In fact, the same technique can be used for other projections too, but since they usually require less hand drawn frames it isn't as common a method I've seen.
On modem hardware designed to render textured triangles, there will be no advantage to pre rendering tiles from that angle. Draw the tiles square and use texture coordinates to map the images to the isometric tile shape.
Good point - I second that. There are big advantages to going true 3D with an isometric system, such as the ability to let the player rotate the view.
Taking it one bit further, you really do want to go full-blown 3D with a fixed camera perspective and orthographic projection these days. Not only was the historically-accurate way of doing this simply difficult for the artists, but tall,large,and overlapping objects or paths were very, very painful to account for on the programming side -- not impossible, but needlessly difficult when the whole issue can simply be side-stepped today by using proper 3D. And it complicates everything, not just rendering -- pathfinding, collision detection, even the simplest of game logic becomes needlessly tangled in the old way of doing it. And as a bonus, when using the full 3D method, you get proper lighting if you want, so things like bump-mapping and parallax mapping and shadows all work seamlessly.
(...) and orthographic projection (...)
