So, CGA was 4 colors if you used an RGB monitor but could actually output 16 colors if you used a composite monitor via artifacting. (It could really get beyond that. There are demos of CGA outputting 1024 colors).I experienced such different game than looking videos of them now, 4 shade of green CGA monitor, pc speaker, etc..
This is more the memory of gaming on a PC in the 80s... thjat really not how I remember say test drive or King Quest1
View attachment 656285
It was more like this:
View attachment 656286, but all shade of greens.
There something I imagine nice but also an developer nightmare, how vastly different everyone system playing those games were....
King's Quest on actual hardware (an original IBM PC & Monitor).
View: https://www.youtube.com/watch?v=Km7UB9CRMyE&t=37s
The Apple 2 did the same thing. Actual graphics were just an on/off bit. Depending on the previous bit, it would change the output frequency. On an RGB monitor, you'd only see certain colors. On composite, you'd see more.
I made a simple program for editing Ultima 5 Apple 2 tiles here:
https://github.com/BehindTimes/U5Lzw/tree/master/U5Apple2TileEditor
and you can experiment with changing the bits to get the desired output color. I'm sure there are better ways to do this, but I personally find it somewhat confusing. (Even emulators aren't perfect. The real hardware, the lines above, depending on the color, could influence the lines below to add even more colors.)
But this is also why King's Quest's resolution is 160x200, whereas the actual monitor resolution is 320x200. It uses dual bits to create the artifact color.