>M-4 (Midway 1977) Did this game use a backdrop or overlay?
My Midway M-4 parts catalog confirms backdrop and interior side scenery pieces as follows:
---------- 0626-00902-01SC Side scenery card - left 0626-00902-02SC Side scenery card - right 0626-00903-00SC Background scenery card ------
No mention of transparent overlay piece.
Sizeable list there. And that doesn't include non-cpu games.
Got a nice start with Atari Tank 2, Atari Pong, Monaco GP, and a minor portion of PSE Desert Patrol artwork....which there is also an interior overlay piece that provides text description such as "Time Remaining", "Score", etc. That piece hasn't been found yet.