What are 8-bit graphics anyway?

July 28, 2018

While trying to make a retro game with an 8-bit feel, I’ve often found myself straying far from the track and clawing my way back. Being without relative restriction on making the assets and game on a modern computer, it begs the question, what is “8-bit” anyway?

To be exact, 8-bit is simply a way to explain how memory was structured in a computer. The more bits, the more powerful the computer. The reason it was popular for so long (early 70’s to mid 80’s) is that it was cheap, worked, people knew the system.

8-bit certainly means different things on different consoles, as they were put together differently by different companies, all working to different goals. Some aspects of 8-bit lay at different ends of the spectrum: Does it need to be as cheap as possible? Do we want make the best we can from parts that can be sourced?

This can be seen in the stark contrast of graphical ability in 8-bit machines. To accompany the processor, wildly different graphics and sound chips were used. Some could handle lots of colours onscreen, colourful sprites, or have higher resolution. Some could only handle 2 colours per sprite. The difference is so massive that it really begs the question: what are “8-bit” graphics anyway?

The Spectrum could handle two colours per 8×8 pixel tile from a set palette of 16 colours. The NES 3 colours per 16×16 pixel tile, from a bank of 4 unique palettes made up of 53 unique colours. The master system — the king of colours — had a restriction of a whopping 12 colours per sprite, from a 6-bit, 64 colour set palette.

In later years many games would use sprite overlays to increase their sprites detail. This would come at the cost of sprite flickering, from having too many sprites on the same scanline. Emulation doesn’t suffer from this problem, and sprite flickering is not something 8-bit graphics enthusiasts are too keen on recreating.

More colour density make the graphics look less and less like “8-bit”.

So without restriction, 8-bit can look less and less classic. This is what it means to stray from the track, the more you pursue what is “technically possible” — the extreme capabilities — the less you retain an 8-bit feel.

With my project I started out with the best of intentions as NES game. The below image is using those restrictions (albeit in widescreen).

Here it is running in I-CHR debug tool by Kasumi

And on an actual NES:

Thats all fine and well, but without restrictions, it quickly descended into something that was just using the NES palette, with parallax scrolling, tons of colours and 3D effects, as below:

Maybe it’s not the graphics, what makes an 8-bit feel?

So I got to thinking, if the NES can be pushed to “NES + “, and that route is always something that the game will eventually move toward — unless we run the game on an actual NES — what restrictions can help to retain a NES-like feel?

1. Fixed backgrounds

Ditch the parallax, remove multiple palettes per tile. Make the tiles strictly 4 colours, with one of the colours fixed in all tiles. (classic for NES was the use of black as the shared tile colour)

2. Constrain Sprites to a grid

One of the things that make NES games look the way they are, is the tile grid. Now we don’t pay much attention to it, but remodeling all the sprites to try and make them fit in a grid can help with a modular look that most NES games had.

Old Pete VS new Pete, the old one wasn’t constrained in size. The new one is 2 16×16 units.

Seen here against the NES Splatoon prototype, Pete fits in better with grid, enabling background graphics to work more in harmony with the sprites. One could even call this the “NES modular” system, like Lego (Lego figures are exactly 4 bricks tall)

3. Only use 1 colour for sprite overlay

Games like Megaman did this, and happily retain the NES feel (it was on the NES after-all). This should be done as sparingly as possible.

In the end, these restrictions should help to solidify the look of an 8-bit game, on the NES at least!

As always, comments, questions etc. are very much welcome below.

* Despite what kids in the playground told you their uncle had access to, Super Mario Bros is not on the Master System or Spectrum, these are just a made up graphics for illustrative purposes.