Good Egg Galaxy is accessible from the Terrace observation dome, and is the first galaxy available to you once you reach the Observation Platform.
Star 1: Dino Piranha
Run between the fences on the left, to the underside of the first planet, and up the side of the tower. At the top, talk to the Luma, who will turn into a Sling Star. Spin the Sling Star to reach the bigger Launch Star, then spin again to be hurled towards the second planet, in the shape of a dumbbell.
On the second planet, you need to collect five Star Chips, while avoiding the rolling rocks. Watch out for the muddy areas on the ground, which considerably slow down your movement. Once all five Star Chips have been collected, they will turn into a Launch Star. Activate the Launch Star by spinning, to reach the third, bean-shaped, planet.
Here you can touch the ? Coin to produce some Star Bits to collect, which will give you a hint on which way to go. To proceed you will need to defeat the Piranha Plant, and a Sproutle (vine) will appear. Climb the Sproutle by spinning to reach the fourth planet.
This planet looks like a hollowed-out apple, and is the first one which will kill you if you fall off it into the black hole in the middle. Avoid the spiky plants and rolling rocks and proceed along the path. At the other end of the planet, you'll find a giant Piranha Plant, which can be destroyed by spinning into one of the rubbery green plants so that the plant hits it. Watch out for your aim, though, because if the green plant misses the Piranha Plant, it will spring back towards you and knock out some Star Bits you are carrying. When the Piranha Plant is dead, a Sproutle will appear.
Use the Sproutle to reach the fifth planet, which is another bean-shaped one with a stone structure on it. Climb the structure, defeating the enemies along the way, until you reach the top. There you will need to spin to destroy the crystal and release a Launch Star. Fly off to the final planet, where you will meet the boss, Dino Piranha.
This is your first boss fight of the game. To defeat him you will need to spin his heavy-looking tail into his head, so that it flies up into the air and hits him on the head. You will need to do this a total of four times. Each time he will get angrier and chase you, so try and avoid his attacks.
If you need to replenish your health during the boss fight, as well as the obvious coin trapped in a crystal which you can destroy by spinning (or which the boss will destroy as he chases you), there are also a couple of what look like glowing carrots on the ground. Shoot these with a Star Bit to release a coin. Watch out for these carrots in other levels.
Star 2: A Snack of Cosmic Proportions
You start on the same initial planet as for Star 1, but you need to leave via the horizontal walkway rather than the top of the tower. Talk to the blue Luma who will transform into a bunch of Pull Stars. Use the pointer and the A button to navigate the Pull Stars, and use the Launch Star to fly off to a new part of the galaxy.
In this section you will travel between three small planets connected with Launch Stars (two of which are hidden in crystals). The first planet contains spiky plants, the second rolling rocks, and the third looks rather like a Yoshi egg. The system of Launch Stars seems rather confusing at first, but basically the planets are connected in a circular fashion. The Launch Stars allow you to progress forwards round the circle (spiky plant planet to rolling rock planet to Yoshi egg planet to spiky plant planet again) if you ignore the Launch Star in mid-space between each planet, or backwards round the circle (spiky plant planet to Yoshi egg planet to rolling rock planet to spiky plant planet again) if you activate the Launch Stars between each planet.
Your immediate goal is to collect 100 Star Bits to feed to the Hungry Luma on the Yoshi egg planet, which you can do by defeating enemies with Spin Attacks, and collecting Star Bits from crystals and shooting stars. Remember to collect coins to replenish your health if necessary. Talk to the Hungry Luma and shoot 100 Star Bits at him to make him transform into a new planet. Use the new dark red Launch Star to fly to this planet.
Here you need to progress up the planet, opening crates (by spinning or stomping) and defeating enemies as you go. You can destroy spiky plants by spinning the green rubbery plants into them. At the top of the planet, use the Launch Star to fly to the capsule-shaped planet you have been orbiting for a while.
You will start on the outside surface of the planet, where you will find several Goombas and crystals holding coins or Star Bits. More importantly, one crystal will reveal a hole to the interior of the planet. Once inside, the game temporarily restricts all movement into a 2D plane, but with a new twist: the gravity can pull you either to the bottom of the screen or to the top, depending on where you are located, and indicated by the arrows on the walls. Nonetheless, you should proceed in a straightforward manner to the top of the planet, where you will find a Launch Star to take you to the final, pentagon-shaped, planet.
Although it isn't obvious at first glance, don't worry, you cannot fall off this planet. You'll see the Star in the middle of the planet, but you won't be able to reach it yet. You need to collect five Star Chips scattered about the planet. Once all have been collected, five Pull Stars will be revealed. You need to use the Pull Stars to collect the Power Star in the middle. However, because the Power Star is not placed along a straight line between two Pull Stars, it takes a little experimenting to collect. One method is to activate the top-left star, then before you reach it activate the bottom-right star. You should find you swing round in mid-space and grab the Power Star.
Star 3: King Kaliente's Battle Fleet
You start on the same first planet as for the previous two Stars. This time the Launch Star is on top of the house in front of you. If you haven't already explored and found how to get onto the roof, you need to go through the orange pipe on the underside of the planet. Take the Launch Star to a new planet.
Here you can rescue a Toad caught in crystal, break some crates, and shoot Star Bits at the bubbles on top of the tree, if you wish. To continue on, Spin Attack a coconut to make it hit the spiky plant, revealing a Sling Star. Use this to reach the neighbouring planet.
On the next planet, avoid or defeat the Goombas, and spin a coconut at the Pokey then jump on its body to kill it. This time a Launch Star will appear.
This Launch Star will take you to a small planet containing two Chomp Heads. If you wish, you can use the pipe on the underside of the planet to reach the interior. Here you can touch the ? Coin to reveal a Rainbow Mario suit, which you can use to defeat the Goombas and the Chomp Heads outside if you're quick enough. To progress, use the Launch Star.
You will land on the underside of a bigger planet, with Chomp Heads, Goombas, and electric fences. Head to the top side, which is pretty busy with more Chomp Heads, Goombas, and Bullet Bills, amongst other enemies. There are plenty of coins here if you need to replenish your health. You need to head up the stone structure and break the crystal in the middle to reveal the Launch Star, and use it to reach the first of two ships.
A pair of enemies on the second ship are firing melons at you. Simply Spin Attack the melons, which will hit them back at the enemies. Remember this action, as you'll need it in the boss fight later. When the two enemies are defeated, a walkway will lower connecting the two ships. Meanwhile there are more optional things you can do on the first ship, including jumping and spinning near the ship's wheel to release some Star Bits. (Later on, this guide will not go into so much detail, and will leave you to explore and discover such non-essential things yourself).
On the second ship, climb up to the stern and break the crystal for the Launch Star, and use it to reach the underside of the final planet. Here you can talk to a Luma for an explanation of coins embedded on the surface of planets. Make you way to the top side.
Boss Fight - King Kaliente. Caliente means hot in Spanish, and this guy certainly is that. Avoid the fireballs he fires at you. When he fires a melon at you, spin it back at him so that it hits him, which you'll need to do a total of three times. The first time you spin the melon back at him it should hit him straight away, but for the second and third times he will hit it back at you, so you need to keep hitting it back until it damages him. After he is hit the first time, in addition to the fireballs he will release blue fiery enemies at you. You cannot seem to defeat these, so just avoid them. Once he is dead, collect the Star.
Star 4 (Speedy Comet): Dino Piranha Speed Run
This Star is available when a Prankster Comet is in this Galaxy.
Do the same as for Star 1, only within a 4 minute time limit.
Star 5 (Purple Comet): Purple Coin Omelet
This Star is available when a Purple Comet is in this Galaxy.
You need to collect all 100 Purple Coins, with no time limit.
You will travel between the same three planets (spiky plant planet, rolling rock planet, Yoshi egg planet) as in Star 2, only with no Goombas. Each planet has Purple Coins on its surface, 40 in total. There are also 10 coins on each path forwards and backwards between the planets reached using the Launch Stars, 60 in total.
The most efficient way to collect all 100 Purple Coins is to collect all the coins on the planet surface, activate the Launch Star and activate the second Launch Star while in mid-space, then repeat for the next two planets.
Star 6 (Hidden Luigi): Luigi on the Roof
This is one of the Hidden Luigi Stars, available after Luigi sends you a letter with a photograph of this galaxy. The title of the Star gives Luigi's location away, but like all the hidden stars you don't actually see the title of the Star until you obtain it.
Luigi and the Star are on the roof of the house on the first planet, accessible via the orange pipe on the underside of the planet. Talk to Luigi to obtain the Star.
To save time, you can just triple jump onto the roof from the start so you can avoid using the pipe.