My friend Richard just sent around an email pointing out that Tim Schafer, founder of Double Fine Productions and former designer at Lucas Arts, in a "fit of Cake-induced Grim nostalgia," after a celebration of the 10 year anniversary of Grim Fandango, has posted the PDF of the original Grim Fandango Puzzle Design Document. To quote Richard's email directly, "OMFGHOLYSHIT!!!"
Richard and Baz just finished playing through the Legend of Kryrandia PC game and were complaining about some of the puzzles. I pointed out that they should play some other adventure games of that time period if they wanted to see difficult puzzles. To quote Tim's post, "People said the puzzles in Grim were super hard, and I’ve always maintained that this was due to a deep character flaw or mental illness on the part of the player. But now, reading this again, I’ve realized that holy smokes--Some of them puzzles were nuts. Obscure. Mean, even."