Before 1976, developers of copyrightable material had to work harder to protect their interests. If a game was made before 1976 and has no visible copyright claim or other evidence that the manufacturer intended to protect the art through copyright, then you can ask your local intellectual property (IP) attorney about the possibilities. Note that the company being defunct (e.g., Genco) does not necessarily mean there is no owner of the IP they developed.
.................David Marston