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However, what you're asking is pretty ambivalent. Art similar as created on 8-bit console hardware? Art limited to 8 bits per pixel, or for a system with a total hard limit of a 8-bit palette?
8 bits, in the sense of color, means a limit of 256 colors simultaneously displayable on the screen. That's not much of a limitation for sprites outside their actual environment of games, and if the sprites run in a 16-bit or better display environment, that's all you need to note.
However, if you're running a game on an actual 256-color limited hardware, you must keep in mind that you must use that 256 color palette for ALL your sprites and background, in which case.... it's much harder, yes.
Older hardware, such as the mc68000 based Amigas had a limit of 32 colors, albeit there was a mode where you automatically got a darker shade of the color, which for most intents and purposes meant 64 colors.
As for, say, 8-bit nintendo