So it did! Thanks - will add it - wonder why I thought it was med res?
It runs in interlace mode, which effectively doubles the vertical resolution, but makes the thing migraine inducing flickery to look at.
Most emulators, including MAME, are still cheating when it comes to interlace games and running them as if they were genuinely twice the vertical resolution, rather than rendering alternating fields and reproducing the ugly flicker / artefacting.
This will change one day, but for now that's how it is.
A lot of Namco 3D games used the same interlace modes, as did early Midway stuff (Tapper etc.) Sega were one of the few to use genuine medium resolution monitors and invest in the significantly higher spec hardware needed to power them (they basically have to draw almost twice as many pixels)