Really good watch, would watch again, and can recommend.
First off, Lin Shaye ("Insidious") absolutely steals the scene whenever she is on scene, that lady knows how to "old lady horror" if anyone does.
Like most decent horror movies, this one is fueled by stupid. Even in the unlikely scenario of any of it being real, on top of the unlikely scenario of finding "the game", how insanely bored and out of options would you have to be to do something that involves drawing blood? I had to digress here because it's my main beef with the movie, but it spoils things if I continue.
I actually really like this concept, essentially playing a "life at stake" game with the bogey man, a sort of "cheating death" trope ("Final Destination"), but more direct.
The movie does a fantastic job of expressing the effects of the Midnight Man, and gives some excellent imagery. Otherwise it's a "survive in the house till morning" sort of thing, and while the overall plot isn't all that special, there were some really good twists and the Midnight Man is such a good concept.