This pack is in early development. Things are still incomplete and textures are subject to change.
This is a resource pack that changes the Minecraft textures to look like the simplified versions used in the official Minecraft trailers and promotional art. The focus of this project is currently on Minecraft 1.7.10. This pack is open source.
Alternatively there are the popular Bare Bones by RobotPants, who has all rights reserved and Trailer Vision by DiamondIsntHere and Roxtro, with a very accommodating license (not a comprehensive list). Both are excelent quality. But those two are made for more recent minecraft versions then what I'm focusing on.