I feel like there’s way too much color for this to be ‘retro’. It seems you are limited to using 16 colors at once, but those colors are drawn from a 24-bit palette unless I’m missing something.
EGA also used 16 colors out of a possible 64 (although the the 16 colors from CGA were most often used), and the colors here also approximate a selection from the EGA palette: https://en.wikipedia.org/wiki/Enhanced_Graphics_Adapter#/med...
https://en.wikipedia.org/wiki/Amiga_Advanced_Graphics_Archit...
As contemporary of 8-bit arch's it seems retro enough to count.