I played Space Dungeon on the Atari 5200 when I was 15-16 years old. Loved it. Had no clue there was an arcade game. Around 1997 a nut named Crazy Frazee announced that he had a rare Space Dungeon arcade game and would auction it in a chat room to the highest bidder. I participated, but the bidding went too high for me and I dropped out as the 2nd highest bidder. A while later, a friend (Al Kossow) who knew I wanted one pointed out one for sale on David Countrymen's page. I contacted him and arranged to have the machine shipped to me at a very fair price. It's one of the five Qix hardware games and therefore had all the problems they usually have. Bad video RAM, bad power supply, leaky battery, etc. I did all the fixing that needed doing... installed PC-AT power supply, patched the program ROMs to work without the coin processor and replaced the horrid board-eating battery with a NVRAM board designed by Mark Spaeth.
Around 1999 I was browsing someone's web site who had a ton of NOS control panel overlays and spotted a NOS Space Dungeon CPO listed as "unknown". I bought it for $35. Someday I will install it, too.