You can't do that anymore. You need theme to sell these days. Heck, even in pinball's heyday during the 90s you couldn't sell without theme. I've got numbers, but non-themed games were very poor sellers in comparison.
EDIT: here are those numbers.
Licensed Games
Sales over 20,000: The Addams Family
Sales over 15,000: Terminator 2, Twilight Zone
Sales over 10,000: Indiana Jones, Star Trek: NG, Star Wars
Sales over 5,000: Demolition Man, Bram Stoker's Dracula, World Cup Soccer '94, Creature From the Black Lagoon, Doctor Who, Corvette, Judge Dredd, Jurassic Park, Hook, Last Action Hero,
Pirates of the Caribbean, Lord of the Rings, Simpsons Pinball Party.
Unlicensed Games
Sales over 20,000: None!
Sales over 15,000: None!
Sales over 10,000: Getaway, Fish Tales
Sales over 5,000: White Water, Road Show, Theatre of Magic