Hey DeadRinger!
The problem with compatibility seems to be a system requirements issue. HHBB was made to take advantage of GPU power, specifically that of an external Nvidia or AMD brand GPU, the game uses quite a bit of GPU Instancing and at times is rendering thousands of meshes at once, not to mention the second half of the game that takes a complete graphics turn to extremely high resolution.
Try updating your GPU drivers, see if that helps at all.
I'll relay this message to Kaleb the programmer, and we'll keep specs like yours in mind for future titles to ensure maximum compatibility.
Best Regards