On my Mac Pro 3,1 (Early 2008) running El Capitan, both Houdini 16.5.378 and Unity 2017.3 run perfectly. Inside Unity, if I try and use Houdini Engine in any way, Unity instantly disappears. If I have the Houdini Engine package imported into a project, trying to play or open a new scene in that project will insta-crash Unity. I was able to get around that by removing all Houdini Engine files from that Unity project.

Is this fixable with my current setup? My Mac Pro is my primary dev box for Unity/games, and my target is Xcode/iOS currently. I'm aware that exporting the Xcode project from Unity Windows for building on the Mac is an option, but I would prefer not to if possible.

Thanks for any help.

Could you check your Unity Editor log file for any errors?

I'd recommend updating your macOS if possible.

I skimmed the log but nothing popped out as an obvious error to me. Would posting the log it here be helpful?

Unfortunately I can't ‘officially’ upgrade OSX. Sierra and High Sierra are not supported on 2008 Mac Pros. There are hacks that get around that, which I may try at some point.