[BUG] I can't cr8 the GA of "Adventures of Shuggy"

I believe that was free at one point, and mass free games are removed.

It was given away for free at some point is the reason you can't find it.

I had a long discussion about similar problem with some games i own today and it turned out, that if a game was given somewhere for free in the past, then it is not possible to create a giveaway for that game here (removed by creators of SG from the database i think). It doesn't matter, if you have that game in your Steam Gifts Inventory or did buy it before or after it was given away for free somewhere.
One user did provide an interesting link unfortunately there is no informations about the reasons why a game made it at the list anymore (according to the comunity there used to be information about that in the past) and the list is NOT only listing "banned/removed" games, but every single bundle branded game as well (so those you still able give away using SG's system)

But glad to see, that not only new users like me are facing that problem and are not able to find good explanation in the FAQ/SG Rules/Guidelines. I assume you did some research ofc :)

edit: some misspells
edit 2: Your game is on page 3, you it used to be in the database and noone forgot to add it