Really good watch, would watch again, and can recommend.
Abbi Butler is amazing in this, a sort of paired down version of "Would You Rather".
Not only do the characters do a wonderful transformation through the movie, reminding me of a twisted double helix, but the idea of the physical lengths she goes to are fantastic.
If you're into horror-torture, then you've probably seen the "SAW" franchise, and "Would You Rather", and I don't think this will disappoint. It's not "Hostel", but there are definitely enough scenes that will either make you uncomfortable or uncomfortably happy.