I'd sell it for $2500 and invest in non-trademarked domains... $2500 profit for a day's work isn't all too bad.
But if you're set on trying to sell it, make a fan page for the game (so it wouldnt be seen as cyber squatting), or make it a religious site
I'd just sell it and invest into better domains though.
What are the typeins on it? If it's getting some good typeins then you may get more than $2500 for it, or forward domain to amazon.... but if typeins arent that great, I'd sell it for $2500, or try to get an extra $500 from the guy since he is so set on having that name.