Space Invaders.
After spending years trying to find the machine my father traded for a brick BBQ in the backyard (1990s), I ended up buying Wotto's project. I restored it and LOVED playing it. It was a big hit on a NYE party at my place, and shortly after, my 2 year old son started having nightmares about the backglass. One night my wife was turning off the lights and she walked past the gamesroom and the reflection from the moon must have caught the reflection of the mirrored backglass and that was enough for her to ask me to move it on ASAP. A blanket was put over the headbox until I sold it - regretfully. I had a deal with the missus - Spacies out - Medusa in. So I bought a Medusa and NO ONE ever complained again. Recently, I tracked down another Spacies (via the forum whilst posting this story) and TOAD's missus sold her game to me - which I will wait until my daughter turns 10 to restore.
My missus does not know I have another Spacies..