The Fullbright Company
Details and Conditions
The only source I was able to find in regards to any policy statement was a reply from the official Twitter account for the game Gone Home in which they state they approve of YouTube monetization. From my experience, YouTube does not consider social media posts as confirmation. However, the videos I have uploaded for the game Gone Home has received copyright claims for the music used. If you're not featuring the music in the game for your video, I would suggest contacting the developer for a proper statement that you can use in case YouTube asks for it.
What it Means
Videos and streams ARE allowed
You CAN monetize on YouTube and Twitch with ads and subscriptions
You MIGHT be able to sell or charge for access to your content (this would include Twitch "subscriber only" streams)
Any licensed IP or music not owned by the publisher are not covered by this policy