nah, that's just the monitor... CGA was mono on a mono monitor but otherwise it was ugly black, cyan, red and i forget what colour, blue maybe, been quite some time since i saw CGA... CGA was the beginning of the adoption of color monitors, so many people first saw it on mono
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yeah, it was literally CMYK (magenta, cyan, yellow, black)
ok, white, magenta, cyan, black...
some more examples of this typical CGA display from those days (late 80s) https://www.mobygames.com/game/16195/galactic-conqueror/screenshots/dos/1064275/
My monitor was definitely capable of RGB. Windows 3.1.1 worked, full color in MS Paint, etc.
This was like 25+ years ago, so I don’t remember the details. Just that when I tried to play it in full color it was garbled and choppy. Monochrome worked though.