Super Paper Mario/Chapter 1: Lineland

Chapter 1-1: The Adventure Unfolds
Enemies: Get it? Unfolds? Paper? Ha ha. Yeah. Anyway, just move far to the right side of this screen, jumping on the enemies to kill them. In the house there, use Tippi to reveal a hidden door. You'll meet Bestovious, who will teach you how to flip to 3D (Press the A button as Mario). When you do, a meter will appear at the top of the screen. If it runs out, you'll lose 1 HP, so be careful!
 * Goomba - 1 HP, 1 Attack, 0 Defense
 * Squiglet - 2 HP, 1 Attack, 0 Defense
 * Sproing-Oing - 4 HP, 1 Attack, 0 Defense

Go back outside, then flip near the door surrounded by blocks in order to get into it. In the next area, continue going right and flip near the green pipeto pass it. When you get to a giant gap, flip again and walk on the path to the left.

When you get to a large wall that seems impossible to pass, flip and keep going. In the next area (yup, another one), hit the ? block to get a Mega Star that makes you...MEGA MARIO!! You can kill any enemies and break bricks by touching them. When your power runs out, you'll find a Star Block, which you can hit to end this chapter.