I think the original Dark Castle only supports black & white. There was, however, a mid-90s re-release by Delta Tao with colour graphics. Grab that one
from the Mac Garden. It'll work with setting the display to 256 colors as suggested by IIO above.
If you're looking for the b&w graphics because of nostalgia, you could try to emulate a Mac Plus on OSX 10.4 with Mini vMac. First download
on this page here. Not sure what the performance will be on a Clamshell, might be too slow.
Wouldn't that thread better fit to the Games subforum?