HumbleBundle have evolved and found new ways to bleed me dry. This is the first GOG bundle that I'm aware of. I actually own all of these games on Steam but none of these on GOG. A little dissappointing that Kingdom Come Deliverance is only the base but quite a few of the others do include DLC that I don't own on Steam. Kingdom Come: Deliverance's The Royal Edition DLC is actually cheapest on GOG so I guess that's something. ITAD have the historical pricing for the bundle at $76.68 with 4 of the games new to bundles. I assume they are separating the GOG versions from the Steam versions as Vampyr has been in a bundle at least once already but they are saying this is the first time for this version.
Claiming the games was pretty easy. You need to link your GOG account to Humble then just click on the links on your purchase page. Please note, you do not get extra keys for any games you already own.
Tier 1 - 4 Items - $11.93
Kingdom Come: Deliverance - Steam page
Thronebreaker: The Witcher Tales - Steam page
Tier 2 - All 7 Items - $17.89
Wasteland 3: Colorado Collection - Steam page
Greedfall Gold Edition - Steam Page
Darksiders III: Deluxe Edition - Steam page
Edit: Added some extra info about claiming.
Edit 2: Added ITAD info.
(profanity) I got Kingdom Come 2 weeks ago
FYI it doesn't run great on Steam Deck… strangely unoptomised, considering BG3 and Cyberpunk were fantastic experiences.