But lots of people are posting negative reviews, saying "It crashes a lot"
Thanks to Orca9999's tireless efforts, it looks like we have a work-around, and a potential culprit.
http://steamcommunity.com/app/254200/discussions/0/154644598513676391/?ctp=4
Short version; it looks like, under some circumstances, something is going wrong with something DX11 related. The solution is to force use of DX9 - put
-force-d3d9
Into your Steam Launch options and it 'should just work' (tm)
Cheers to Orca9999 for working out what it was!