The Game I Want to Give Away is not Showing up Under "Select a Game"?

I am trying to give away a copy of the game Nuclear Shot, but when I type that name in the search field when making the giveaway, it does not appear. I am not sure why this is, is it possibly because it sees I won a copy of it and it thinks I am trying to regift it? (this is a second copy, not the one I won) I don't think that is the case anyway though because I have seen a few people who were regifting something and it obviously went through for them anyway. So I am stumped! Is there something else wrong with that game? And if I can't figure it out I guess I can trade it with someone instead hehe. Thanks in advance for any help!