I've been wondering about this for a while as I'm completely new when it comes to the laws involved in media. Say an author comes up with a story. He makes a comic book. A company publishes the book and distributes it. Is it the original author who came up with the idea that can ultimately decide "I want this game company to turn the comic into a game" or is that now in the hands of the publisher? My common sense is saying the author still holds the rights but I'd rather know for sure. Thanks :)

As far as I know, if the author didn't give its rights to the publisher, then yes, it owns the rights to whatever can be done with its IP. If the author gave its rights to the publisher, then no.

Depends on the contract language. Plenty of comic book publishers will want either an assignment or broad exploitation rights as to the property and will use very broad language to that effect.

Broad language that pertains to the entire property will be interpreted as applying to the entire property. Language that fails to strictly limit rights to distribution and reproduction of the comic book to comic books/graphical/literary works may arguably extend to audiovisual and performance works (i.e. video games). It's actually a common issue in clearance and chain of title matters for movies based on comic book properties. Typically, if an author wants to retain those rights he has to clearly hold them back and make the limitation of the license as clear as possible.

Comic books are written under the "work for hire" exception to copyright law. This essentially says that the company created the work and owns the copyright, not the author.

I think there's a move underway in the comics industry to abolish the use of WFH, but I'm not current with comic books. That's the way it's been until recently anyway, and I think it still is.