Slammer

The Slammer is an unproduced Bally Manufacturing prototype, known today only through a single surviving backglass. According to secondhand recollections from a Chicago-area arcade retailer who obtained the glass from a former Williams employee, only one example was ever built, and its playfield was left unfinished and never fully printed; the software reportedly caused the CPU to lock up frequently, and the unfinished playfield and boards were eventually discarded, leaving only the glass.

What made the design notable was its unusual gameplay concept: rather than standard flippers, the player controlled a rubber-covered sling with left and right buttons to fling the plunged ball up the playfield toward targets, a mechanic likened to the video game Breakout translated into pinball form. It's unclear whether the game included pop bumpers or where exactly its targets were positioned.

Because it never left the prototype stage and left almost no documentation behind, The Slammer remains one of pinball's more mysterious might-have-beens, known to history through a single glass and one secondhand account rather than any produced units.