haha, i was looking at some metal slug images to help learn new styles of pixel art, and as I was practicing doing some stonework, I thought that i'd make a tutorial for it, so that people can make some awesome looking rocks, for their games.
okay now lets break this down with words.
step 1. make your general shape, this may take a while but once you're satisfied with the shape, you can move on to step 2.
step 2. Now that you have your rock/stones shape going, pick a lightsource, personally and keeping with metal slug, I/they chose to put the light coming from the top face of the rock/stone. Once you're lightsource is picked start to shad the outline of the stone, according to the lightsource.
step 3. now go ahead and fill in the faces of the rock/stone, according to the lightsource. (ie. top face gets a medium base colour where as the bottom and sides of the rock/stone get a dark colour.)
step 4. this step doesnt really follow with lightsource but adding a lighter shade of the top face's base colour helps add dimmension to it, and make it seem more realistic in the end.
step 5. no within that lighter shade surrounding the top face, add some light that should more or less follow the light source, as well as shade the top face (thats on the far side of your lightsource) a slightly darker shade of its base colour.
step 6. just a few finer details, fix up some of the lighting that you dont feel certain about, and remove the outline in the dark area of the rock/stone.
step 7. now some detail work on the dark area of the rock/stone, add an outline to it in a darker colour than that of the dark area of the rock/stone.
And with some determination and practice it could end up looking like mine did.
Enjoy, and hopefully I'll be able to make some more tutorials. Hope I helped someone.
~Tutorial by John (Nitemare60), Inspired by Metal Slug.
[By the way, send me a pm, if you have a request for a tutorial or need help in general and I'll get to you as soon as I can]