As you may have remembered when I brought up 'hardest games' here in Off Topic, I write a 'top 6' games list that appears in the monthly technology supplement of a UK national newspaper (The Observer, AKA the Sunday edition of The Guardian). All quite abstract/academic etc. Before I've done 6 best game romances, 6 best game books, 6 most unusual game genres etc.
This time my editor expressed great interest when I mentioned we could do the '6 rarest games'.
Which is where I turn to you lot for suggestions (you know us journalist scum; when we're not rewriting a Wikipedia pages as articles we're asking other people to do our work.

Now, I'm not looking to actually pick the top 6 by a quantifiable quality, such as 'in order of price' or 'in order of copies made'. Partly that's because it would be impossible to quantify, but the reality this list is really the 'top 6 most interesting rare games'.
So, I'm after unusual games, games with unusual stories, perhaps one that's famously faked to the point the fakes become a collectible, one with a dramatic story to the way a copy came to be found; that kind of thing. Obviously a couple do need to have silly, silly high price tags.
And it can be games of any genre, for any format! One could also perhaps be a game collectible, like a silly expensive bit of cardboard, but I'm far more interested in games.
Of course, Dodonpachi Campaign version should likely go in, if I haven't already featured DDP too much in these lists!