You are selling a game that you “really do not want to sell” sounds like, but he is a good friend and you are thinking about selling to him because you like him alot. I have sold several items that are special to me for various reasons and i made an agreement with the buyer that .....if you ever decide to sell this you got to promise me that i have first chance at it because i will probably want it back.

There is nothing wrong with that at all. You think enough of this guy that you are willing to sell him a game that you really dont want to get rid of so you make a gentleman’s agreement that he has to give you first chance back at it if he no longer wants it. Absolutely nothing wrong with that what so ever.