Double Fine's game jam runs until April 28th. Three tiers, with the highest tier ($15) containing full games, tiers 1 and 2 are prototypes.
...During Amnesia Fortnight, Double Fine takes a break from whatever they're working on ("amnesia"), splits the company into teams, and gives each team a couple of weeks to make a new game ("fortnight").
Pay what you want to get the 4 prototype games (available 28th April):
The Gods Must Be Hungry
I Have No Idea What I'm Doing
Pay $5 (about £4.03) or more to get Amnesia Fortnight 2012 and 2014 prototypes:
The White Birch
2 Player Productions Daily Videos (2017) - HD 1080p Downloads
10% off Humble Monthly for New Subscribers
Pay $15 (about £12.10) or more to get Double Fine games along with the Little Pink Best Buds prototype:
Hack 'n' Slash
Little Pink Best Buds
25% off Double Fine Adventure Blu-Ray Discount Code
Stacking Metacritic: 80% (9 critics, 7.9 from 92 users)
, Steam: Very Positive 92% (586 reviews)
Costume Quest Reviews of an earlier/alternative version: Metacritic: 77% (39 critics, 7.5 from 64 users)
, Steam: Very Positive 94% (1277 reviews)
Iron Brigade Metacritic: 75% (7 critics, 5.2 from 38 users)
, Steam: Very Positive 83% (376 reviews)
Hack 'n' Slash Metacritic: 73% (14 critics, 5.2 from 34 users)
, Steam: Mixed 61% (382 reviews)
Spacebase DF-9 Metacritic: 49% (4 critics, 3.1 from 51 users)
, Steam: Mostly Negative 20% (2702 reviews)
"All of the prototypes included are DRM-free and for Windows only. The full games, from Double Fine, are available DRM-free and on Steam. Please check out the full system requirements prior to purchasing."