Quickly explained goals of Bad Piggies:
Pig: The most basic goal, and one that you'll find on every level. Simply make a contraption that will get the pig to the finish line. Doesn't matter if it's slow, fast or messy.
Stopwatch: You need to get the pig to the finish within a specific time limit. The time is shown on the icon, and a timer will appear in the top-right-hand corner on levels with this goal.
No breakages: You've got to reach the finish line without your vehicle crumbling apart and without wheels snapping off mid-journey.
Star crates: On levels with this goal, one or more star crates will be placed within the level. You've got to collect them and then reach the finish to achieve this goal.
King pig: On some levels, you'll have a giant pig that takes up four spaces on the grid. You've got to ferry this monster porker to the finish to score this goal.
Object restriction: To get this goal, you'll need to hit the finish line without using the tool that's shown on the icon. Could be a generator, a specific type of wheel, or a TNT crate. Your guess is as good as mine. May be better.
Explore the galaxy in the franchise's first open-world game.