I think the real question here is how you define "fun", or rather, whether or not racism in a videogame is appropriate.
Now, please hold your incoherent rantings while I give my completely off the cuff, unjustified and soon to be misunderstood opinions.
RACISM IS INAPPROPRIATE! There, I said it. Just so no one misunderstands me.
Example 1: The KKK makes a videogame about killing black people. The only thing is: you don't know that it was funded or created by them. Is it fun? Probably not. Is it appropriate? Definitely not. I seriously doubt that example is under discussion.
Example 2: A video game company releases a video game in which the main character is racist. But, it shows no violence to any minority group. The video game company says that they did that to, "give the character some depth". Is it fun? Is it appropriate?
Truthfully, I have no idea. You have to answer this one for yourself.
Example 3: A video game shows a particularly violent cutscene in which the main character is beating a black criminal to death. It is the only black male who dies in the entire game. There are no deragatory statements made by the main character towards African Americans, or any other race. But this one scene has stood out from the game. Is it fun? Is it appropriate?
Example 4: You play as an undercover cop (the main character). Your job is to infiltrate a local gang to find out its hierarchy, where the money is going, etc. The entire gang, and every criminal in the game is black. But so is the cop. Is it fun? Probably. Is it appropriate?
I, strangely enough as it sounds, believe that racism is appropriate, and even fun or funny IN CERTAIN SITUATIONS. Those situations are pretty rare. Racism is an unfortuate piece of our societies and our histories. Even to the point of being bred into us. As humans we have not evolved much, if at all in the past 2-3 thousand years when our different races began to collide with one another. We may have built fabulous civilizations, cities, communities, but all we were ever born with was a brain that can barely function out of the tribal societies our ancestors lived in. We truly are a tribal people. You see it every time you see a sports fan cheering on the local team, or everytime someone gives their hometown or country undeserved accolades. Or everytime a black male is walking around an all white neighborhood.
It's natural. It's understandable.
That doesn't make it good.