CORRECTION to the below: I never read ETERNAL VOWS - that is, as the wiki states, the THIRD comic series. I've only read the first two - but they are worth checking out per the following...
OP:
Both of those comics are really very good and any attempt at a sequel or follow-up would do well to read 'em before proceeding with a screenplay. The first (2-issue) series is short, sweet, frosty, and 100% suspense/action/horror, w/ beautiful artwork. The artwork and pacing on the second (4-issue) series is less impressive - but there are two individual scenes from that 2nd series that I would rate as tense and/or freaky as anything from THING '82 - high-praise indeed. One is a long, dialogue-driven scene in the jungle around a campfire (shades of the fade-out from Carpenter's film), the other is a potential standoff where the lights in the room suddenly go out. Awesome stuff.
I presume Dark Horse still owns the rights to the content of those six issues and publisher Mike Richardson has been pretty open about the HELLBOY films being essential to keeping his lights on the past 20 years, so I imagine he'd be open to negotiating for a "based on" credit...
Also, yes, the video game was cool for... 20-60 minutes.