Complex sentence: Robby is delighted until he sees where Pinga got them from the bottom of their tower and the tower starts to wobble, and despite Robby's attempts to stop it falling it crashes to the ground in the ground with Pingu underneath.
Split into simpler sentences: Robby is delighted until he sees where Pinga got them from--the bottom of their tower! The tower starts to wobble, and despite Robby's attempts to stop it falling it crashes to the ground in a heap, with Pingu underneath.