Okay, I hope this'll be a good idea, coz I'll be making levels out of each chapter, (I'm currently making a level out of chapter 2):
Chapter 1: Fall of Marblatius
Marblaxia's forces attack the homeland of the marble, Marblatius. The marble must rescue all the gems from any further destruction by Marblaxia. The level ends with the departure of a ship that brought about the last bomb on Marblatius.
Chapter 2: The Pursuit
Totally airborne level. Pursue the ship that was referred to in Chapter 1 while avoiding debris. You end up in Marblaxia's secret base.
Chapter 3: Co-Enemy
The marble is detected by Marblaxius on camera, a slave and faithful servant of Marblaxia. The marble's task is to find Marblaxius. He then sends different booby traps to prevent the marble from going into the control room. The level ends with Marblaxius, being impressed by the marble's skills, becoming an ally.
Chapter 4: Nuke Factory
Marblaxius orders the marble to disarm all of Marblaxia's forces' ships and sneak into the weapon factory while avoiding the weapons themselves. The marble must destroy all of the machinery in the weapon factory. This level ends with Marblaxia standing right in front of the last machine to be visited.
Chapter 5: Weather Machine
Marblaxia then uses the last machine, a weather machine, to cast a tornado in his base while he is on his ship flying by it. Marblaxius and the marble are both thrown away and must go into the tornado to be able to find the last machine and destroy it. The level ends with the machine's destruction.
Chapter 6: The Final Showdown
Marblaxia is pissed that he sacrificed his own base and failed to destroy the marble. Marblaxia then goes to the last undestroyed section of the base. The marble chases him down and sees Marblaxia on his throne. The marble must steal the 5 gems that give Marblaxia his power. The level ends with Marblaxia's surrender and Marblaxius's farewell.