Mario...IN SPAAAACE!!!Mario is on his way to visit Princess Peach so that they can observe a comet streaking past the Mushroom Kingdom together, but suddenly, Bowser returns once again to kidnap Princess Peach. The attack launches Mario into space and he awakens on a strange small planet, where he meets Rosalina, a person that protects the cosmos and living star-shaped creatures called the Lumas. After taking Mario to her Comet Observatory, she explains that Bowser has stolen all power from the Comet Observatory to fuel his army and create a new kingdom for himself. Mario must retrieve all the stars for Rosalina so the Comet Observatory can venture to the center of the universe where Bowser awaits...Released in 2007, Super Mario Galaxy is a Platformer for Nintendo's Wii with gameplay similar to Super Mario 64. Though unlike Super Mario 64 as well as Sunshine, the gameplay is noticeably more linear with less focus on exploration. In this game, Mario flies around from planet to planet with the help of Rosalina and The Lumas to retrieve Power Stars. There are additional gameplay elements with the Wii Remote such as spinning to attack enemies and jump higher. Power-ups return to this series, two of which are from the original game that started it all.The game is also notable for being the first Mario game to feature music played by a live orchestra. Though Mario series veteran Koji Kondo was in charge of the soundtrack, the orchestrated bits were done by Mahito Yokota, who was previously the composer for Donkey Kong Jungle Beat. As a result of working on this game, Yokota has become the go-to guy for orchestral arrangements for games that Kondo has composed for.A direct sequel, Super Mario Galaxy 2, was released on May 23, 2010.
Added Alliterative Appeal: The names of many galaxies. The Kitchen observatory alone gives us the Beach Bowl, Bubble Breeze, and Buoy Base galaxies.
Already Done for You: After you rescue him from the haunted mansion, Luigi will go out looking for Stars on his own. However, he invariably gets stuck in whatever galaxy he's in, forcing you to go rescue him to obtain the star. There are also several galaxies in which Toads have already retrieved the Star, you just have to go get it from them.
Antepiece: Nearly every boss level uses a game mechanic or enemies with unique defeat strategies (if the boss is a King Mook) that will be used to defeat the boss. 3 examples:
The Kamella's Airship Attack level revolves around throwing Koopa shells to break chests and progress through the level. Kamella is defeated by throwing the shells she summons at her.
Major Burrows's minions are the Undergrunts, enemies you have to ground-pound to get them out of the ground, and then jump on them/spin them to kill them. Major Burrows is a very large Undergrunt, so naturally, the same strategy is required, though you have to chase him once he's out of the ground.
Baron Brrr is an enlarged Li'l Brrr. The Li'l Brrrs are defeated by spinning them (they float) to extinguish their ice cloud and bring them to the ground. They will turn darker and bounce around the ground, trying to fall into ice water to revive themselves. If you kick them by walking into them in this state, they will be defeated, and drop a coin. Their Baron is very much the same, but with added attacks.
Apocalypse How: After the implosion of the sun Bowser created at the universe's center implodes, it's heavily implied that, aside from Mario and Rosalina, nothing was actually saved, per se—rather, the Lumas recreated everything.
Baby Planet: Practically all of them. Heck, some planets aren't much bigger than Mario himself, yet still have enough gravity to hold him down. The most extreme example is in Deep Dark Galaxy, where Mario will encounter a bonus planet that, once he undoes a screw to reveal a circle of coins, is constantly shrinking, and no matter how small said planet gets, Mario won't escape from its gravitational pull until the planet vanishes completely. Also quite literal as some Lumas (which are literally babies) will explode into planets when you feed them enough Star Bits. Some will explode into galaxies later on in the game.
Back Story: The Library allows the player to read Rosalina's backstory, which explains how she got into outer space and became the "mother" of Lumas. It also describes her longing for the home and family she left behind.
Bait-and-Switch Boss: Bowser Jr.'s final appearance in the game. He kidnaps Peach and fires canonballs to destroy Mario's steps... only to watch the final battle between Mario and Bowser.
Batman Can Breathe in Space: Actually justified for Mario early in the game (his Luma presumably gives him this ability). As for everyone else, though, the trope applies (likely via Toon Physics).
Battle Tops: One of the bosses, Topmaniac, is a top. He is the leader of the Topmen, smaller sentient tops.
Big Boo's Haunt: Several galaxies. Ghostly Galaxy is the classic haunted mansion iteration, while Deep Dark Galaxy is an underwater variation.
Big Eater: A lot of the Lumas will ask for large amounts of star bits - so large, in fact, that they explode and somehow create planets.
Brick Joke: Halfway through the game, the napping yellow Toad will mention the word rotisserie. In the Grand Finale Galaxy, you can find the Toad Brigade roasting a rotisserie meat.
Bonus Stage: Some of the pipes lead to underground areas where you can collect more star bits, coins, or 1-ups.
The first boss in the game is Dino Piranha, and the last boss (not counting Bowser) is Fiery Dino Piranha. In fact, Dino Piranha is the first Star in the first galaxy (not counting the Gateway Galaxy), and Fiery Dino Piranha is the last Star in the last galaxy (not counting Prankster Comets or bonus galaxies.
In the opening of the game, you're in the Mushroom Kingdom, celebrating the Star Festival. Guess when and where the Grand Finale Galaxy is situated?
The first challenge you do in the game is play hide-and-seek with bunnies on a small planet. The last Hungry Luma level involves you finding bunnies in a smaller, snowy planet.
Boss Arena Idiocy: Topmaniac would be invincible if he would just get rid of that electric fence around his arena.
Boss Arena Recovery: Many of the boss arenas have little lights or plants on the ground that you can shoot star bits at to produce coins to restore your health. Some of the fights even have coins and star bits in the arena itself. And as if you weren't constantly picking up Star Bits during both the preceding level and boss fight, hitting a boss enough times to start their next phase usually causes dozens of Star Bits to pop out of them.
Boss-Only Level: Bonefin Galaxy. The only mission in it begins on the Starshroom, and when Mario uses the Launch Star, he's launched to the only actual planet in the galaxy. The battle against Kingfin begins immediately, and the mission ends when Kingfin is defeated and Mario can collect his Power Star.
Yoshi actually makes a brief appearance in this game as two different planets: one in the save file screen, and the other in Space Junk Galaxy.
During the prologue, when Bowser captures Peach and carries both her and her castle high up into space, when Mario starts to go after Bowser as he is about to fly away with his airship brigade to save the princess, a Magikoopa immediately swoops down and attacks him, sending Mario toward a small planetoid nearby and knocking him unconscious. According to the tie-in trading card game, that Magikoopa is actually Kamek.
Camera Screw: Most of the time, you can't control the camera's position; several challenges in this game would be a lot easier if you could actually see what you're doing (though the game is a lot better than Super Mario 64 in this regard).
Cerebus Syndrome: For all its cheerful charm, the game includes some melancholy elements. This includes Rosalina's Tear Jerker storybook, as well as the ending, where the entire universe is destroyed due to a massive black hole and all of the Lumas throw themselves into the black hole to neutralize it and recreate the universe.
Chainsaw Good: Topmaniac has a red-hot one, with ten yellow spikes on its side.
To damage Bowser, Mario must spin on Bowser after getting a platform to explode under him. Because Bowser is smart enough to run away, Mario usually has to chase him by going the other way.
Colossus Climb: Megaleg and Heavy Metal Mecha-Bowser. Also present in the first level of Honeyhive Galaxy, where Bee Mario has crawl all over the Queen Bee's massive body in order to collect the five star chips embedded in her hair.
So off the wall here, it had to be mentioned twice. The final fight between Bowser and Mario have them fighting on an exposed battleground inside an artificial star. Not to mention Melty Molten Galaxy, which takes place on a planetmade of lava! Justified since you're in space, where there is no air or other fluid to convey the heat.
Co-Op Multiplayer: The Co-Star Mode in both games. The sequel expands on it by including an orange Luma.
Cosmetic Award: Get 9999 star bits? The coconuts turn into watermelons.
Critical Annoyance: The "low battery" sound and icon implemented in the game for the Wiimote. Really just there to annoy you since they game will helpfully pause the game when the battery finally bites it. Similarly, an alert sound will play when you're down to one wedge of health...and won't stop until you replenish it.
Darker and Edgier: This time, Bowser goes beyond kidnapping the Princess, and actually trying to taking control of the whole Galaxy/universe. And said Galaxy gets destroyed and recreated. Add in the aforementioned Cerebus Syndrome too and the result is a Mario game with more than just the usual Princess that needs saving. Downplayed in that it is still quite cheery, though.
Deadly Dodging: Many levels require you to lure Bullet Bills into crashing into things you need blown up.
Deliberate Injury Gambit: Sometimes it pays to let an enemy hit you in order to lose an inconvenient power-up. (I'm looking at you, Spring Suit.)
Dem Bones: Kingfin and Dry Bones. The former is a skeleton shark and the latter are Koopa skeletons.
Divine Assistance: Rosalina, for the one or two parts she actually decides to aid you.
Do Well, But Not Perfect: In the levels where you have to swim behind Guppy and go through the rings that he puts out, if you're such a fast swimmer that you actually catch up to Guppy, the knockback from when he hits you can easily cause you to miss a ring.
Dramatic Wind: Bowser's flapping hair is rather hypnotic, isn't it?
Dub Name Change: The galaxies all had English names even in the original Japanese version. A few of them stayed the same, but most were changed despite the fact none of them really sounded very Engrish-y and arguably better in some cases (for instance, Melty Molten Galaxy was called Hell Prominence Galaxy in the Japanese version).
The sheer amount of unused stuff found upon cracking the game open is enough to make one's head spin. Everything from unused boss designs to unfinished planets can be found in there.
An almost-finished planet, the Starman Fort, resembling an excavation site, still has its files inside the game, albeit with messed-up gravity, but nevertheless is much more complete than some of the planets that made it to the final version. It was even supposed to house a bunch of missions, and even the first boss battle according to a concept art!
There is also the alternative hub planet shown at the E3 2005, and an urn-shaped planet with a question mark on it. Another planet has a dozen of climbable poles with some spiked urchins down.
Mario himself has some unused moves, such as punching and tennis moves. An unused 3D model for a kart exist also, along with Donkey Kong Jungle Beat models.
Dynamic Loading: The Launch Star animations were used to hide the game loading the next planet.
Easter Egg: If you look very closely while on the third planet in Toy Time Galaxy, you can actually see a tiny model train inside one of the cracks in its walls.
Electric Jellyfish: There's a huge one guarding the entrance to the underground lake in Deep Dark Galaxy.
Everything's Better with Penguins: By now, it's a Mario series tradition to include NPCs who are penguins. They show up in Loopdeeloop Galaxy, Sea Slide Galaxy, Drip Drop Galaxy, Buoy Base Galaxy, Loopdeeswoop Galaxy and Beach Bowl Galaxy.
Flight of Romance: Mario and Peach have such a moment after he delivers an epic beatdown to Bowser at the end. He catches her as she falls from Bowser Jr.'s airship and whisks her away with the final Grand Star.
Floating in a Bubble: The Bubble Breeze and Bubble Blast Galaxies. You can also use a bubble to obtain a secret Star in the Gold Leaf Galaxy.
Floating Water: Loopdeeloop and Loopdeeswoop Galaxies both feature a long flow of floating water where Mario plays Manta Ray Surfing.
Free Sample Plot Coupon: Mario's goal is to retrieve the Grand Stars that fuel the Comet Observatory built by Rosalina. Luckily for him, the first of these Stars is the only one that isn't guarded by any of the bosses. Also a case of Back from the Brink.
Gainax Ending: Mario watches as a huge black hole forms in the center of the universe as the Lumas fly into it and cause the hole to implode at first, sucking Mario, Bowser, Peach, and everything in the universe into it, then explode violently. After that, Mario faces a huge Rosalina that says new baby stars are being born as a result (complete with baby crying). After that, Mario and the gang wake up in the Mushroom Kingdom, only it's now a fusion of all the worlds that he visited.
Game-Breaking Bug: Although this game has received top-notch QA, some glitches exist, making Mario die if he spend too much time orbiting around a planet without actually landing on it (especially frequent with Luigi, by abusing the long jump/lock-on spin, or with some glitchy planetoids like that bouncing ball), but they merely send you at the start of the level. However, it is painfully played straight under some circumstances. In the final level in front of Bowser, no less, where you can cause it to freeze before the final confrontation with him by managing to go up to him before the Event Flag that activates the meteor shower, and then try to activate said Event Flag. It's possible.
Gangplank Galleon: Deep Dark Galaxy hosts a pirate ship that shows up in several missions.
A God Am I: Not quite as literal as in the sequel, perhaps, but Bowser has definite shades of this trope in this game. Seriously, he's trying to destroy the universe so he can recreate it as his own galactic empire. With Princess Peach as his (probably unwilling) queen. Granted, it blows up in his face at the end (rather literally, too), but then the universe nearly gets destroyed in the aftermath anyways.
Gratuitous English: The galaxies all had English names even in the original Japanese version. A few of them stayed the same, but most were changed despite the fact none of them really sounded very Engrish-y and arguably better in some cases (for instance, Melty Molten Galaxy was called Hell Prominence Galaxy in the Japanese version).
The first planet of Gateway Galaxy is grassy and somewhat flowery.
The first planet of Good Egg Galaxy has some grassy elements.
Guide Dang It: The Cosmic Comet races become much easier once you learn the technique to get a speed boost at the beginning; in fact, this speed boost is practically required to beat Cosmic Luigi. The only problem? The game not only does not tell you how to get it, it doesn't even tell you it exists.
Have a Nice Death: If you get to the end of the Battlerock or Dreadnought Purple Comet missions without all the purple coins, the Gearmo will mock you for not trying hard enough and then take away one of your turns.
Helpful Mook: Plenty! Cataquacks, Koopas, Bob-ombs, Bullet Bills, and green Topmen, to name a few.
Homage: What with the tiny planets, way of slinging around space, and the plot of the storybook (not to mention Rosalina herself), the whole thing seems to be inspired by The Little Prince.
Hornet Hole: Honeyhive and Gold Leaf Galaxies. At least the bees are friendly.
Hub Level: The Comet Observatory in the first game is probably the most rudimentary example yet in the Mario series; all it does is connect the various worlds, with no secrets or bonus Stars of its own, unlike Super Mario 64 or Sunshine.
An Ice Person: Ice Mario, who's literally made up of ice. He can skate on both water and lava, creating a hexagonal block of ice where ever he skates.
Megaleg is defeated by making Bullet Bills break the glass cage
To defeat an Undergrunt Gunner, Mario can ground pound on the cockpit, which is made of glass.
Incendiary Exponent: Fiery Dino Piranha is a fiery version of Dino Piranha, the first boss in the game.
Infinite 1-Ups: There are several 1-up mushrooms scattered around the observatory hub which respawn if you enter a door and come out again, not to mention the frequent letters you get from Peach containing five 1-up mushrooms each (or 20 if you're Luigi.)
Insect Queen: Queen Bee or the Honey Queen is the queen of all bees in the universe, and dresses in appropriate regalia. She's also playable in Mario Kart 7, where she is decidedly smaller. She's probably the only King Mook (or King NPC) in the Marioverse that's female, as opposed to King Bob-omb, King Goomba et al.
It's Up to You: Double subverted. Hey, looks like Mario doesn't have to get all the Stars himself. Luigi and the Toads are going to help him! But then they get captured or stranded, so in the end, you still have to do all the missions, same as if they weren't helping you.
The Sweet Sweet Galaxy is mostly made of cakes and biscuits.
"Bouncing Down Cake Lane" in Toy Time Galaxy features oversized cakes, chocolate bars, an ice cream cone, popsicles, lollipops, and huge ice cubes.
Lost Woods: Honeyhive and Gold Leaf, which are a bit more whimsical than your standard Lost Woods, but they do have giant bugs, lots of bees (including a power-up), and in Gold Leaf, rabbits. Enemies that are standard fare for these worlds appear too, like Wigglers and Monty Moles.
Macro Zone: The Toy Time Galaxy features many huge toys.
Meaningless Lives: It's pretty easy to stock up on lives. Good thing, since you start with 4 lives whenever you begin playing (regardless of how many you had when you finished your last session).
Miles Gloriosus: The self-appointed leader of the Toad Brigade. One of the other Toads lampshades this. In the Grand Finale Galaxy, upon learning that the captain is being promoted to Royal Guard Commander, one Toad says "But the leader is the least brave of all!"
Moon Rabbit: Just in case you're wondering why there are rabbits living in planetoids.
Multi-Stage Battle: The first two thirds of the final battle against Bowser take place on two different planets; the third and final stage takes place inside a star.
Musical Gameplay: Coins that pop up out of blocks or bushes will have their usual coin SFX be in tempo and harmony with the backing music. Additionally, when fighting King Kaliente, every time you hit one of the coconuts (or it hits him) a musical cue plays.
Mutually Exclusive Powerups: Most combinations of the power-ups in the game (Fire Flower, Ice Flower, Spring Mushroom, Bee Mushroom, Boo Mushroom, Red Star and Rainbow Star) are impossible. Attempting to combine them will result in either the old power-up losing its effect or Mario kicking away the new power-up.
Never Say "Die": In Rosalina's storybook, when it's revealed that Rosalina's mother is dead, it's described as "She's sleeping under the tree on the hill".
New Game+: Getting all of the stars with Mario unlocks Luigi, and lets you play through the game again with him. He runs faster and jumps higher than Mario, but has less traction and is flung farther when an enemy touches him. He also loses extra oxygen when spin-boosting through water. And, his Cosmic Comet races are harder.
No Damage Run: The daredevil comets force you to complete a challenge without taking any damage. Usually it's redoing a boss fight, but one of the more sadistic ones - "Lava Spire Daredevil Run" in Melty Molten Galaxy - forces you to replay an entire level like this, namely, the "The Sinking Lava Spire" mission. There's also the second segment of "Scaling the Sticky Wall" in Honeyclimb Galaxy, when meteors can, in a single hit, rob you of your bee suit, and send you falling to your death by black hole.
Noble Demon: The Spooky Speedster keeps his word and hands over the Power Star when you beat him in the races.
Nominal Importance: For some reason, the English translation didn't give names to any Lumas, while the original Japanese (which called them Chikos) did indeed have names for some of them. You know the Luma that grants Mario's ability to spin? The one that Rosalina introduces with the line, "To save your special one, you'll need to power to travel through space. Luma can give you this power. I will entrust you with his care"? He is named Tyke in the Japanese version. They also didn't mention the name of the black/dark brown Luma who is always at Rosalina's side and in the observatories. His name is Polari, after the star Polaris. This oversight makes the storybook a tad confusing in the English version, since upon meeting the Lumas for the first time, Rosalina makes a point of thinking up names for all of them.
Not Cheating Unless You Get Caught: In the second mission of Beach Bowl Galaxy, "Passing the Swim Test", you have to retrieve a golden shell in the ocean and bring it back to the coach in order to pass the test and get the Power Star. However, there aren't any golden shells lying around on the ocean floor. One of the other penguins eventually clues you in that the actual way to pass the test is to find a penguin carrying a shell and steal it from him.
One-Hit Kill: Thwomps and Tox Boxes can flatten Mario, which always kills him instantly.
One-Hit-Point Wonder: The daredevil challenges reduce Mario's max health to one unit, which means that any damage will kill him.
Opening the Sandbox: If you collect all the Stars in the galaxies as they become accessible to you, you'll very quickly reach the point where you can take the remaining Star missions in pretty much any order you want.
Racing Minigame: Several. To start with, there are the four Cosmic Comet races. In two levels ("A Very Spooky Sprint" in Ghostly Galaxy and "Racing the Spooky Speedster" in Boo's Boneyard Galaxy), you race a helmet-wearing Boo to a Power Star. You also race a group of penguins in "Faster Than a Speeding Penguin" in Sea Slide Galaxy, and there are at least four levels in which you encounter rabbits who want you to chase them. Then there's the "Surfing 101" mission in Loopdeeloop Galaxy and the "The Galaxy's Greatest Wave" mission in Loopdeeswoop Galaxy, in which you have to make three laps around a watery course on a manta within a (fairly generous) time limit. The game designers apparently think players can't get enough racing.
Rainbow Speak: In dialogue, important words are often highlighted with various colours.
Recurring Boss: Topmaniac has to be fought four times: twice in regular battles ("Topmaniac and the Topman Tribe" in Battlerock Galaxy and "Revenge of the Topman Tribe" in Dreadnought Galaxy), once in a daredevil battle ("Topmaniac's Daredevil Run" in Battlerock Galaxy), and once as part of a speed run ("Topman Tribe Speed Run" in Dreadnought Galaxy). Kamella and Bowser have to be fought three times each (Kamella in "Kamella's Airship Attack" in Space Junk Galaxy, "The Underground Ghost Ship" in Deep Dark Galaxy and "Ghost Ship Daredevil Run" also in Deep Dark Galaxy, Bowser in "The Fiery Stronghold" in Bowser's Star Reactor, "Darkness on the Horizon" in Bowser's Dark Matter Plant and "The Fate of the Universe" in Bowser's Galaxy Reactor) and there are several other bosses you have to fight twice.
Reincarnation: A major theme of the game. Lumas are born from star dust, and grow into stars, moons, and planets, the latter of which have people on them. Eventually, they decay and crumble back into star dust, which goes on to create new Lumas. When you add in the ending, this game looks very, very Buddhist.
Rise to the Challenge: "The Sinking Lava Spire" in Melty Molten Galaxy. "Sunbaked Sand Castle" in Dusty Dune Galaxy is an unusual example; Mario is trying to make it to the top of a tower before it fills up with sand, but the game turns the controls upside down, so it appears that the ceiling is trying to crush Mario before he gets to the bottom.
Say My Name: Peach screaming for Mario's help. It doesn't help that, outside of her letters, it's her only line in the game.
Peach: MAA-REE-OOO! HELP ME!
Scenery as You Go: The platform maze in the "Pull Star Path", "Pull Star Path Speed Run" and "Purple Coin Spacewalk" missions in Space Junk Galaxy, as well as the ice bridges in Bowser's stage.
Scenery Porn: Just look at some of the space backgrounds. They look absolutely amazing, and in 480p no less. For example, in the first level of Melty Molten Galaxy, there's a sequence which consists of Mario shooting through several launch stars in a row. The main point of the sequence seems to be to show off the impressive graphics of the volcano level.
Sci-Fi Writers Have No Sense of Scale: Those are not galaxies, those are clusters of asteroids, or small moons at best. And there is no reason to assume Mario is doing more than visiting the part of the galaxy relevant to him but each gateway looks more like it's selecting from a solar system. Also, along with that, Bowser Jr.'s airship armada can not be viewed that huge a couple of thousand miles away, as that "galaxy" is smaller than even the other galaxies in the game..
Toon Physics aside, it might have been more sensible for each of the galaxies to be called 'solar systems,' each found within the same galaxy. There's also a few mentions of Bowser setting up shop in the center of the universe, which isn't a place (or rather, is every place). 'Center of the galaxy' would have worked much better.
Self-Imposed Challenge: Getting all 150 purple coins in "Luigi's Purple Coins" in Toy Time Galaxy or "Purple Coins on the Puzzle Cube" in Gusty Garden Galaxy (only 100 are required for the star). Yes, both are actually possible! Not enough for you? Here's a bunch more! The developers also made it so that getting Starshrooms are optional.
Sequel Escalation: This game is more of a successor to Super Mario 64 than Super Mario Sunshine, and it begins with Bowser stealing Peach's castle. Super Mario 64 took place entirely in and around that castle, and Bowser just hoists it off like it was nothing. That's a clear sign that the stakes are much higher this time.
Space Zone: Naturally, everything in the game can be considered this because it takes place in outer space. Space Junk Galaxy is the best example. It contains discarded space junk, including old rocketships and floating debris.
Spring Coil: The dreaded Spring Mario powerup, which wraps a spring around Mario.
Stealth Pun: The Dirty Tricks of Major Burrows. As in, the dirt that he digs through! Most of the levels are like this to some extent.
Suspicious Videogame Generosity: There is always a Life Shroom just before a boss or difficult section, often sold by a Luma Shop. And a Musical Spoiler where it changes to the 'Tension' theme. Both of these are in the sequel, too.
Tactical Suicide Boss: Several examples. The Bomb-Boos that Bouldergeist spits out are the only way to defeat him. Same deal with King Kaliente and the coconuts he occasionally lobs at you. If he'd just stick to fireballs, he'd be invincible.
Tennis Boss: King Kaliente is defeated by reflecting his coconuts at him.
Throw The Mook At Them: Bouldergeist, a ghost that encases itself within stone. Normally it would be invincible to Mario's attacks. However, during the fight it will occasionally throw a black rock at Mario, which will become a Bomb Boo, which in turn Mario can use against the Bouldergeist to break apart his stone casing. When it reaches its vulnerable phase, guess what it still intentionally spawns?
Timed Mission: The speedy comet challenges, as well as the ammo depot mini-games have time limits. Some of the purple coin missions are timed as well.
Title Scream: Just like the rest of the 3-D platformers, Mario screams the name of the game whenever you start it up.
Took a Level in Badass: Bowser. In previous titles, his goal is just to kidnap Peach. In Galaxy, capturing Peach seems to just be a bonus for him; his real goal is the conquest of the entire universe. (See A God Am I above).
Toy Time: Toy Time Galaxy is the Trope Namer, and features oversized toys like a toy train on a train track.
True Companions: The overarching theme of the storybook is how Rosalina and the Lumas are like this.
Tunnel King: The Undergrunts and Major Burrows, who are mole-like creatures, are pretty good at digging.
Turns Red: Pretty much every boss in the game gains new attacks once you get a couple of hits on them.
The Unfought: The UFO Bowser uses from the opening sequence simply lifts Peach's castle into the air and into space. It also appears in the cutscene just before the final level and during the ending. It has absolutely no impact on the gameplay though.
Under the Sea: Three main galaxies (Beach Bowl, Sea Slide, and Deep Dark) and four mini-ones (Buoy Base, Drip Drop, Bigmouth, and Bonefin).
Unlockable Content: Getting all of the Stars with Mario unlocks Luigi, and lets you play through the game again with him. He runs faster and jumps higher than Mario, but has less traction and is flung farther when an enemy touches him. He also loses extra oxygen when spin-boosting through water. And, his Cosmic Comet races are harder.
Unmoving Plaid: Cosmic Mario has Mario's character model with an unmoving texture of a night sky.
Unrealistic Black Hole: Several are localized around planets and are only a couple of feet in diameter. And the black holes are extremely picky about what they want to suck in. In real life, all those black holes in Honeyhive Galaxy (for example) would suck in the entire level and everything in it, not just Mario!
Gateway, Battlerock, Beach Bowl, Buoy Base, Sea Slide, and Freezeflame Galaxies all feature instrument variations in their background tracks depending on what you're doing or where in the stage you're at. Other tracks that change up at will include stage select domes, the ball rolling minigame, rabbit chasing, and any boss fight with Bowser. That a significant number of these tracks were recorded by a full orchestra makes the switchovers all the more impressive.
Additionally, no matter what stage you're in or what song is playing (including Rainbow Star, Fire Flower, or Ice Flower tracks), touching a Sling Star adds a matching harp to the music, with the arpeggio varying in intensity with how big the star is.
Video Game Cruelty Potential: During one mission in Space Junk Galaxy, you'll encounter a Toad trapped in a sling pod. To progress, you have to get him out of the sling pod so you can use it yourself, but the game progresses whether you fling him to a safe spot or kill him by flinging him out into space. Many players get a sadistic kick out of doing the latter. (Not that it ultimately matters, since he shows up again on the Comet Observatory either way.)
The flying saucer seen in the opening, which is equipped with lasers capable of slicing through the ground effortlessly, and which is obviously not from the World of Mario, is never mentioned after the opening.
In the storybook, what happened to the girl's father and brother?
Presumably, they died like the girl's mother did. The girl was gone for a long time after all.
At the start of the game, Peach tells Mario to come to the Star Festival because "there's something I'd like to give you". We never find out what that something is. It may be the Luma.
What the Hell, Player?: In Buoy Base Galaxy, if you talk to the Gearmo after destroying the weight that's keeping the fortress from rising to the surface, he says, "You destroyed the weight! So you just go around breaking stuff, eh? You think that's OK? Breaking stuff?"
Wide Open Sandbox: You only have to get half the Stars in the game to be able to take on the final boss, giving players who aren't going for 100% Completion a lot of leeway in deciding which missions to play.
World Shapes: There are many others, not just spherical ones.
X-Ray Sparks: In addition to the standard usage, if Mario is killed by a shock, he dies as just a skeleton. If Mario hits a coin during the electrocution animation, he's brought to one point of health and gets his flesh back, saving him but looking incredibly unnerving.