Hello, Tutay. :)

In general, I'm pretty sure that if you can't find the game it's "99+%" likely that you're not allowed making a giveaway for it.

Here's a list of games that you cannot make giveaways for.:
https://www.steamgifts.com/bundle-games

You can see in the link above that Gun Monkeys cannot have a giveaway made for it.

(You can use the search functionality from the link above to be able to quickly find out if you cannot make a giveaway for a certain game.)

Thanks ^^

Appreciated. =3.