This is nicely done. As an aside, there was something posted a while back regarding some of the custom workstations that were used to produce art for NES games. One thing I never really considered, but learned from that article, is how artists back then utilized the imperfections of 'pixels' on a TV set to give sprites more richness. In many ways viewing pixel art on a perfect modern display loses something – a kind of 'warmth' or complexity that becomes too 'perfect' on a high-def display.
This is why videophiles never settle for anything less than an analog CRT... all digital displays lose that warm picture and the fatness of the colors.
Note that some of these features require special hardware support in the cartridge. The NES cartridge connector exposes CPU and PPU (picture processing unit) pins, and the simplest games ("NROM") connect ROM chips directly to them. More advanced designs add an additional memory management controller (commonly called a "mapper"):
The animated backgrounds are accomplished by the mapper bank switching the character (tile) memory. The parallax scrolling is accomplished by the mapper counting scanlines and generating an interrupt when the correct scanline is reached, so the CPU can change the PPU scroll registers mid-frame with the correct timing. Later mappers like the the MMC5 could precisely time mid-frame bank changes to support more than 256 tiles on screen at once, and to support 8x8 attribute blocks instead of 16x16.
The ultimate mapper feeds arbitrary data to the PPU to simulate having a bitmapped display with 8x1 attribute blocks (the PPU only reads attribute memory once every 8 pixels, so that's a hard limit). Tom Murphy implemented this with a Raspberry Pi (which isn't ideally suited to the task, so there are timing imperfections causing graphical glitches, but theoretically it could be done without them):
Thank you for sharing -- these are great. I'm always impressed with this style of tutorial which distills a useful lesson into a single image or GIF. These are very clear, interesting, and informative!
There is another game studio that I've been following which does a good job with this tutorial technique as well (Couch Game Crafters). One great example of their work demonstrates creating a shader for animating the visual effect of a toaster moving through a cartoonish pipe [1]
I love this tutorial format. Below is my favorite series, which concentrates on pixel art but is also useful for animation, composition, color composition. Each GIF is a tiny work of art.
This is a nice companion to https://youtu.be/Tfh0ytz8S0k which deals with more technical details of the implementation of NES and C64 graphics. This document reads like requirements to that video's design.
