Free speech is vital to the survival of our country. It should not be illegal to create or distribute a game like Rampage, and the day our government tries to throw someone in jail for doing so is the day I start burning it onto discs and handing it out. But with that said, how much we ought to be able to do things like that is an almost altogether separate issue from whether or not it is morally right for us to do those things.
One question is that of when we should be allowed to do wrong, and the other is that of if it is wrong. Think about smoking. Should a person be allowed to smoke? Absolutely. But does that mean that it is healthy for them to do so, or that it is the right thing to do? Absolutely not. People have a right to dig themselves a grave one pack at a time, but that doesn't make it healthy or moral.
Whoever made that game has a right to make it, but that doesn't mean that they are justified morally. The harm they are doing by making that game is emotional rather than physical, and so they have a right to cause it, but that doesn't make it any more right. While to have a government that works we need to have our laws based on physical rather than psychological protection, that doesn't have anything to do with what is moral.
Newgrounds isn't a government organization, and so they aren't obligated to give everyone a platform. And I hope that everyone at Newgrounds realizes that for me to support free speech I don't have to give everyone equal access to my personal megaphone or printing press. I am not the government and so I am personally responsible for any message I print or otherwise relay. And every person on the Newgrounds staff that has the power to delete that game but doesn't, is personally responsible for the hurt that it causes people.
I hope you all listen to your conscience, and keep in mind that how guilty you are has nothing to do with how many others are also guilty.