Cloud City 4-15 is the fifteenth level of Cloud City. To pass this level with three stars, you should pop all pigs and score at least 143,000 points.
This level is extremely hard because:
Send Han toward the first floating platform, aiming his laser off of the angled metallic slab on the extreme right, trying to detonate the TNT. Second Han should shoot out the chains above the main structure, and the third should aim for the top-right floating platform. All the while, try to blast the TNT in the middle of the level.