Any license is fine, however projects with licenses that can be classified as open source/free-as-in-freedom will get a few extra points. Again, this is not a requirement.
Creative Commons NC (Non-Commercial) licenses are not considered free/open source by both the OSI and the FSF, however you will receive extra points if you use it but not as many as a F/L/OSS license would.
And yes, a 2-D game is fine, however it must fit the theme in one way or another.