Okay, unlike most staircases you see that pop out of the side of the wall, this is meant to be hidden in the middle of a floor. Its not pretty, but its functional, and shouldn't be doctored up (aka using stair blocks in it) because its meant to sit flush with the floor when closed, and when open you'll be using the pistons as steps. its not to complicated and doesnt take up too much space, but does require a space about 8Lx10wx5h at most with the 5th block in height being the floor. Im fairly sure ive condensed it as much as i can compared to the prototype, and i whittled it down to using only 2 repeaters instead of 7, 3 redstone torches, and 6 sticky pistons. It should be a completely feasible project to build in single player (without mods of course) or on a survival server.