I'm probably only interested in the minimum tier Humble Weekly but I was looking around at the other stuff and under the "Curse Premium 30-Day Subscription" it lists
"One free game from GOG.com" as a premium benefit. I have no idea if this is included in the 30-day subscription or only a full year or if the 30 days requires a credit card.
Unfortunately, from what I can tell it isn't any free game (that would be a
little too good to be true), but according to
this page, the options include:
Sacred Gold
Gothic 2 Gold Edition
Empire Earth: Gold Edition
Divine Divinity
Dungeon Keeper Gold™
Darwinia
Tiny and Big: Grandpa's Leftovers
Puddle
Defender's Quest
Megabyte Punch
If anyone is interested in any of those games and it's confirmed to be included with the 30 days, that might make the difference between the lowest tier and $6 tier for someone. :)