I noticed once that the game downloaded via Steam Outlast after the successful launch and the loser of the introductory video hangs.
As it turned out, a bug in Russification and judging by everything for a long time, that is, with every appearance of captions in Russian, there is a hangup when it is not known to correct it.
To solve a problem it is possible switching in the settings of the game itself the language for example in English, after that there should be no freezes.
In the case of a black screen at startup, you can wait a bit, then try to minimize Outlast by pressing Command+Tab and turn it back.