Published Title Publisher
New Title Publisher
Updated Title
Published Title Score Editor's Choice
Published Title Score

Super Mario 3D All-Stars

Purchase on Amazon

Megaleg's Moon

Ben Chard
Jarrod Garripoli
, &
Seren Morgan-Roberts


This page is dedicated to Megaleg’s Moon Grand Star in Bowser Jr.’s Robot Reactor Galaxy. Bowser Jr.’s Robot Reactor is located in the Terrace dome and is the last galaxy to be unlocked in the dome, requiring 8 stars. It is here where you obtain the second Grand Star in the game.

The Starting Planet

When you land on this planet you want to take the oppurtunity to get all the star bits, coins and the 1-Up Mushroom, which shouldn’t take too long as the planet is relatvily small. To destory the glass containters that on the planet you need to have a Bullet Bill lock on and chase you and have it break the casing on impact. This is how you will get access to the warp star and head to Megaleg.

Bullet Bills are great keys for unlocking warp stars.

Megaleg - Boss Battle

To defeat Megaleg you’ll need to start by running up it’s leg while avoiding Bullet Bills along the way. Once you reach the top, just like before you need to get a Bullet Bill to follow you to destroy the first cage the has the Grand Star. When the first cage is destroyed this will trigger Megaleg to produce more turrets and fire more Bullet Bills and produce surrounding gate around the Grand Star.

You may need to stand closer to the turrets to have the Bullet Bills lock onto you. When they start you will need to carry on the theme of having the Bullet Bill break open the barriers that surround the Grand Star.

(1 of 3) Use the Bullet Bills to crack open the first cage

After defeating Megaleg you’ll earn your second Grand Star and be transported back to the observatory where the Fountain dome will now be unlocked.

(1 of 2) Defeating Megaleg is a big step towards your main goal

Defeating Megaleg is a big step towards your main goal (left), you can now use the Grand Star to power up the observatory and unlock more areas. (right)

No Comments
Guide Information
  • Publisher
  • Platforms,
  • Genre
    Action Adventure, Platformer
  • Guide Release
    24 September 2020
  • Last Updated
    8 February 2021
    Version History
  • Guide Author
    Seren Morgan-Roberts, Jarrod Garripoli, Ben Chard

Share this free guide:

This guide for Super Mario 3D All-Stars offers a walkthrough for all three Mario classics.

Inside this guide you will find:

A 100% Walkthrough - For Super Mario 64, Super Mario Sunshine and Super Mario Galaxy.

A complete guide on Super Mario 64, including:

  • A layout of Peach’s Castle, with each course’s location pinpointed, as well as an overview of each course.
  • Walkthroughs for every star, including all courses’ 100-coin star.
  • How to get each of the power-up caps.
  • The location of every single Secret Star found in Peach’s Castle.

A complete guide on Super Mario Galaxy, including:

  • A Dome Overviews page outlining every galaxy found in each Dome.
  • Walkthroughs for every star, including hidden stars and comet stars, found in each galaxy.
  • A guide on how to unlock the Planet of the Trials galaxies.
  • Detailed coin-by-coin walkthroughs of Purple Coin levels.

A complete guide on Super Mario Sunshine, including:

  • Walkthroughs for every shine in every episode.
  • How to find every Blue Coin.
  • Strategies on how to secure 100 Coins on every Course.

Get a Gamer Guides Premium account: