These 2 would be on wanted list, since the backdrop pieces are incorporated into gameplay....especially Gremlin's Safari. Without the backdrop support users would be unsure how Gremlin's Safari really works. This used to be the case with Frogs many years ago when there was little or no artwork support. Frogs gameplay wouldn't make sense unless one had opportunity to see actual cab and how the game works.
While on subject of Gremlin, the Frogs front bezel piece needs to be found also.
>Circus (Exidy 1977) Bezel/marquee with lamps similar to Skydiver
This and Midway Clowns is another needing to be found.
Clowns bezel piece is magnificent.....much better than the gameplay of Clowns. imo Circus sounds were always better than Clowns. I played both games in arcades in late 1970's.
>Subs (Atari 1977) Uses backdrop
I don't recall Atari Subs using a backdrop. I do recall an overlay piece being used with monitor. I'll have to look again. I know I have cab photos on a disc somewhere.
>Tornado Baseball (Midway 1976) In the works. Uses backdrop
Now in Mr. Do's hands after handing piece to Mr. Do on Wednesday.
>Dog Patch (Midway 1977)
Needs everything. bezel, interior side scenery pieces, backdrop.
That's my list.
As for non-cpu games, PSE Desert Patrol still has a couple interior artwork pieces needing to be added. Desert Patrol has an orange interior overlay piece, but also an overlay piece that is mounted directly onto monitor, iirc, that has printed text for indicating remaining time and scores. Without that, only numbers, plane images, and parachute pilots are visible....gameplay wouldn't make sense.