Lee Petty was initially inspired by German impressionism for the game that became Stacking, and he observed how cheap it was for how much emotion it could portray. The Russian nesting dolls came in when Petty was thinking about themes of "identity" and being able to change it. Plus, having a simple character design with no real moving parts made sense within the game's time and budget constraints.
Economy of design also drove Petty to design Stacking around the single mechanic of occupying stacking doll bodies. He half-joked about implementing a hat combat mechanic (but it had "clearly" been overdone) against German nutcracker enemies, and then decided to opt for a simpler adventure game in the spirit of frugality.
Nathan Martz traced the development of Sesame Street: Once Upon a Monster all the way back to a musical toy called "Happy Song," which was about monsters on a plain white background, playing with instruments; Martz was inspired to take on a joyful project after seeing a GDC presentation by Loco Roco creator Tsutomu Kouno. Over time, the "musical toy" gave way to a "collaborative social experience" called Monster Party.
Then the opportunity came up to get the Sesame Street license, and Martz decided to adapt the game to one that teaches lessons from Sesame Street's "emotional curriculum." So, keeping the concept of exploring joy (something he wanted to do as a break from his job writing dismemberment code in Brütal Legend), Martz added an element of education: learning to experience the joy of helping others.
Brad Muir -- "I was the project lead on Trenched
and then I was the project lead on Iron Brigade
" -- introduced some early concepts for his game, which benefited from an "art jam" within the studio's game design sessions. Double Fine artists all submitted ideas for the theme of the fighting robots, including ... giant heads of US presidents, complete with wooden teeth on the Washington bot. And robots that are also castles. And surrealist "Bosch Bots."
Muir sought Double Fine community involvement elsewhere, pulling in ideas like vintage mens' magazine covers and an iron lung-bound commander. Muir lauded the involvement of the whole team in the finished game.
At the end, the team showed the prototype Amnesia Fortnight versions of all these games, then contrasted them with footage of the released products. They were surprisingly similar, suggesting that the Amnesia Fortnights resulted in fleshed-out ideas. Those ideas, as Tim Schafer said at the end of the night, saved the company.