Wow, thank you for such a kind and honest write-up. I'm really glad you got that feeling of uncertainty and imminent danger that I was aiming for.
I appreciate you taking the time to try on a few different machines as it's not something I have access to test on. My thoughts are the same as yours that it is most likely to do with the d3D API versions. I used a few new features of UE4 including Virtual Texturing, which is not supported on certain cards. To fix it I would have to replace every single texture in the game, which unfortunately I'm not willing to do. I fall more into the art side rather than programmer so the crash log probably wouldn't make much sense to me. I have a GTX 1080 so I thought the 10-series would be fine. I plan to release a colour version at some point as many have missed that from the prototype so I may replace the textures then and perhaps there will be less issues.
I know exactly what you mean with the music. I had much grander plans for interactive/adaptive music but so many of the music features in Unreal are still very experimental and new to me ( the next version seems to be much more stable). I think I know what is causing the cut-off music bug too and can probably fix that when I have some free time. It's too many slop SFX playing and they are taking over the music slot, I just need to split them on different sound classes.
Thanks again for taking the time to play and for your insightful thoughts