Double Fine's Broken Age may be an "old-school adventure game," but it's decidedly new-school in a lot of ways. The most immediate of those is the game's gorgeous, high-res art. Perhaps you'd like to play something a bit more... pixellated? Double Fine's got you covered.
The video above from The Phawx demonstrates how to activate the hidden retro mode in the game. You've gotta kick it down to the lowest resolution, then assign a key to the Shay/Vella icon in the button mapping menu. Hit that button and everything goes decidedly grainy. I'd recommend running the game in windowed mode, too.
(And yeah, this tip is currently only useful for backers who already have the game, but worth keeping in mind for when the publicly-available version comes out in a couple weeks.)
I'm not wild about how retro mode looks for actual play—don't expect anything on the level of the two Monkey Island re-releases, which actually flipped back to the original old-school graphics. All the same, a lot of the rooms I've seen look neat in retro mode, and it could make for a fun way to replay the game while waiting for part 2.