It's a double edged sword.
Yes, it's a royalty free game, but they only made like 1000 of them.
Games like Comet, you have to pay a royalty, but they made over 8,000 of them - so a bigger market potential.
Somebody would need an unworn or NOS playfield to get an "all in one" scan on a Cruse Scanner to start working on the artwork.