Game Doesn't Exist?

Either contact support or make a request on the forum if a game you are trying to giveaway is not present on the list of games you can choose to giveaway.
Refer to the FAQ for various other SteamGifts related things, including rules about giveaways.

(F- it, wrote out a nice long thing, was pretty much done with it, was going over some typos and strange wording, pressed backspace and LEL BACKSPACE MEANS YOU GO BACK A PAGE! and then everything I typed out was gone... GG Modern Day Computer, GG.)

Anyway... In short, add the Humble Deep Silver (Re)Bundle (Below Average) to the list as there's been multiple giveaways going on for it recently which are not properly marked.