I am running two OSs from two different partitions, 9.0.4 on one and 9.1 on the other. Both are the Japanese version of the OS.
I was wrong about CMBB running -- when I actually try to play, after the command briefing is cleared by clicking "Continue" and the game screen should appear, the whole system crashes to a gray screen, under OS 9.0.4, and under 9.1, with a type 1 error.
With CMAK, under 9.0.4, I don't even get the game splash screen; the screen goes blank for a short time, then comes back gray and just stays there, with the entire system crashed. Under 9.1, double-clicking the game icon produces an immediate crash to a black screen.
The above conditions apply with antialiasing off, disabling one GPU, at 800x600 resolution at the minimum refresh rate of 56 Hz and only thousands of colors, vice millions, i.e., graphics should be at their very most compatible (and thus minimum performance).
Yet CMBO works fine under both OSs, with the one exception that if I use command+B to review the briefing or ESC to escape to the Finder, when I return to the game it is no longer in color, but in an eerie grayscale in which little is recognizable and the cursor acts very strangely.
I guess Combat Mission just does not like the 3dfx board.