Humble is providing a free copy of a GOG key for Seven: Enhanced Edition
for the next 47 hours or so, but it does require linking your humble account to your GOG account [Edit - and like all the Humble giveaways, it requires subscribing to their newsletter, fwiw].
Hmmm, looks like something, sort of, has gone wrong, at least for me.
Linked my GOG account to HB account, clicked on the "redeem" button.
Got the message that the game was redeemed to my GOG account.
Skip over to my GOG account to find nothing but a 404 screen for where my Seven: Enhanced Edition "order" should have been.
Checked my email - nada.
But when I searched for Seven in the store front, it listed as "OWNED".
Checked my games list in order of purchase date, and there it was, like magic.
No originating detail, just the game, ma'am.
Not sure if it is a glitch, or some kind of streamlining the "Redeem Code" facet of the site, but the 404 page suggests a bug.
Had a similar problem , but the game is in my library despite the error. Check your library.