It was an apple port design, contemporary with early power macintosh, and very late '040s.

adapters exist.

https://www.ebay.com/itm/323722527296

[For the curious, since this IS Vogons...]
https://allpinouts.org/pinouts/connectors/com … h-video-15-pin/

I am guessing here, that the seller is 'very confused' about what the gameport is for, and has plugged a 'mac to vga' adapter onto it.

Needless to say, a gameport does not produce analog level signals, and cannot drive a monitor.

However, being a fully integrated system, it's possible that they used an apple db15 header instead of 15 compact d sub vga for the external monitor header. With the cable in the way of the ideogram markings, I cannot tell for sure.

wierd_w wrote on 2024-02-11, 07:08:

It was an apple port design, contemporary with early power macintosh, and very late '040s.

adapters exist.

https://www.ebay.com/itm/323722527296

Ah yes, I currently have one that came with my AverKey iMicro allowing me to hook up the iMac G3 to another monitor or a capture device.

I guess I could imagine the pinout between the two are different. Weird honestly because I tend to believe that most AIO machines cant be hooked into a separate monitor/capture device. In the case of a Compaq, you could get away with just throwing a dedicated video card but the only trade off would be needing a separate monitor.

EDIT : Just saw your edit, makes sense.