Which Angry Birds spin-off has players build custom vehicles for pigs?

Bad Piggies is the Angry Birds spin-off in which players build custom vehicles for pigs. Instead of firing birds at pig-built structures, players assemble contraptions to carry a pig through each level.

The game was developed by Rovio Entertainment and released in 2012. Players combine parts such as boxes, wheels, motors, balloons, fans, and other devices, then test whether their machine can reach the finish line. Levels can have multiple solutions, making experimentation and engineering central to the design.

Bad Piggies also includes optional goals and a sandbox mode, where players can freely construct vehicles. That gives the spin-off a more open-ended, physics-puzzle character than the traditional slingshot formula.

The title is sometimes confused with Angry Birds Go!, a separate racing game featuring vehicles. Bad Piggies is specifically about designing vehicles for the green pigs, not racing prebuilt karts. It first appeared on September 27, 2012, for mobile platforms and OS X.