You probably played it on a machine with an aging monitor, or that wasn't set up properly. If the electron beam isn't within spec, it won't excite all the phosphor components and you'll get a colour cast. You can see this on classic 9" Macs - after you switch them on, the initial screen image will look blue/grey until the analog circuitry and monitor warm up and it turns white. If the arcade monitor wasn't adjusted properly, it could've looked a bit blue the whole time.