At the beginning they said they're available for any creative purpose, but now I don't see anything saying so, and the help page says: "YouTube cannot give you information about legal liability or other issues that can occur off the platform. You may wish to consult a qualified attorney if you have questions about your use of music."
Your best bet would be to ask them. As a side-note, I too have been wanting to know if it's available for games.
Source: link (beginning blog), link (current help page).