Video Game / Sonic the Hedgehog CD
aka: Sonic CD
"Save the planet from disaster."

"To live a life of power, you must have faith that what you believe is right, even if others tell you you're wrong. The first thing you must do to live a life of power is to find courage. You must be ready to reach beyond the boundaries of Time itself. And to do that, all you need is the will to take that first step...

Ask not what others can do for you, but what you can do for others."

— Words taken from Japanese cover of Sonic CD.

1993's Sonic the Hedgehog CD (commonly abbreviated to just Sonic CD) was one of the games that could be found on the Sega CD, an ambitious Sega Genesis add-on marred by its price tag and an over-saturation of "FMV games". This game introduced Amy Rose, Sonic's cute stalker with a crush, and fan favorite Metal Sonic. It also had an anime opening and ending sequences with Sonic displaying his badassery; two of the few good-looking FMVs on the console.

The setting of this adventure isn't Sonic's home world, but rather the small world in an odd orbit, Little Planet. For one month out of the entire year, it appears over the Never Lake. Little Planet is the home of seven miraculous Time Stones, which have been reported to cause wonders such as recovering the natural world by affecting the passage of time. To witness this phenomenon, Sonic came to Never Lake, but was shocked to find Little Planet in a metallic floating prison, chained to a mountain carved with the distinct face of Dr. Eggman (also known as Dr. Robotnik). The Mad Scientist seeks the Time Stones to rule over time itself and then Take Over the World, so it's up to Sonic and Sonic alone to set things right! Meanwhile, an energetic hedgehog girl calling herself Amy Rose follows her fortune and falls head over heels with the blue hedgehog, unaware that she may soon fall into the strong, cold arms of his newly-created metallic copy...

The main gimmick of this game is a form of time travel. The first two Zones in each Roundnote  have "Past" and "Future" signs; after hitting one of the signs and gaining enough speed, you'll travel into either the past or the future. By default, the future is always bad, a desolate wasteland with worn-down technology that ruined the environment. By destroying the robot transporter in the past, the Zone's future automatically becomes good, with all advances in technology actually working to the environment's benefit and the Badniks in all three periods destroyed. The third Zone in each Round always takes place in the future and contains the typical boss fight; bad future by default, but if you destroyed the generators in the previous two Zones, automatically good. There are also Special Stages where you can collect the seven Time Stones, which gives all of the Zones good futures as a result (and nets you the best ending).

In addition to the Spin Dash, Sonic can do the Super Peel Out, a technique that sends him dashing off with super speed.note  The Spin Dash operates very differently than in subsequent games, likely because it was in its preliminary stages before Sonic the Hedgehog 2 — in CD, it has to be "revved up" for several seconds before you can go.

Sonic CD was the first main post-Sonic 1 game to enter development. Given that fact and the proto-Sonic 2 features, CD is often theorized to be an in-between game that follows the events of the first game but takes place before the second.note  In spite of the similarities to the first game, Sonic CD is considered by many to be the best game created for Sega CD; many say it's the best Sonic title overall. Some go so far as to claim it is the best and most innovative single game ever released for any particular platform. Many believe it could've been even more popular if the Sega CD itself hadn't been such a failure.

The original version of the game was ported to the PC in 1996 and was later included in the Sonic Gems Collection in 2005 for the PlayStation 2 and Nintendo GameCube.

The game was remadenote  in 2011 for release on the Xbox 360 (through Xbox Live Arcade), PlayStation 3 (through the PlayStation Network), Android, iPhone, iPod Touch, iPad, PC (through digital distribution, primarily Steam), and Windows Phonenote . The new engine allowed the game to be released in HD with proper widescreen support. This remake re-release marks the first time that the game's Japanese soundtrack is officially available in the United Statesnote  and the only version since the Sega CD (or Mega CD, as it is called there and in Japan) that Europeans got it.note  It was also developed by Christian "The Taxman" Whitehead, who had it in the works for a while. The remake also slipped one more thing in: Tails as a playable character.

Sonic CD is the Trope Namer for:

Sonic CD contains examples of the following tropes:

  • Action Bomb: Bigbom, a large version of the Bomb robot from the first game.
  • Action-Hogging Opening: Also included in the package is an ending sequence that's equally just as action-packed.
  • Added Alliterative Appeal: The level names. Ditto for the final boss music, "Final Fever."note 
  • Advancing Wall of Doom: During the Metal Sonic boss race in Stardust Speedway Zone 3, Eggman will chase after Sonic shooting a laser from the bottom of his pod. If he hits Sonic, or if Sonic loses the race, it's an instant kill. The pod itself is also invincible.
  • Airplane Arms: Sonic's max running speed has him do this, as well as his legs going into a infinity-symbol shape.
  • American Sonic Is Hardcore
    • Elements from the JP soundtrack that were Lighter and Softer by comparison were replaced with something much creepier for the US soundtrack. Nowhere is this more prevalent than the boss and Game Over music, which are both worthy of horror games; in contrast, the JP boss music was upbeat and seemed to take Sonic's side in the battle by saying Eggman doesn't stand a chance and sampling the "Work That Sucker to Death" lyrics from the Xavier song of that name, while the game over music just had a sample of the opening theme, "Sonic - You Can Do Anything" (specifically, the "Toot Toot Sonic Warrior" lyrics) that sounded like it was coming from a dying record player, as to indicate Sonic's adventure is temporarily coming to a halt.
    • Inverted, as far as the cover art goes. The North American boxart for both the Sega CD and PC versions have Sonic snatching a Time Stone just out of reach of Metal Sonic, while the Japanese SCD boxart has Sonic and Metal Sonic moments away from coming to blows, and the PC boxart looks like it would also work for an action-packed Sonic movie.
  • Alternative Foreign Theme Song: The North American version not only changes its theme song, but also changes four-fifths of the soundtrack.note 
  • Arc Welding: As mentioned above, it's generally considered by fans to have taken place in between Sonic 1 and Sonic 2, but it was later considered to be a prologue of Sonic the Hedgehog 4.
  • Artifact Title: The 2011 remake is not distributed on a physical medium, let alone a CD. Sega tries to Hand Wave this as claiming the "CD" now stands for "Chrono Distortion".
  • Art Shift: Of the musical variety. Unlike the Present and Future levels, the music for the Past levels is your run-of-the-mill computer-generated BGM. This music also wasn't changed between the JP and US soundtracks, which could lead to some Mood Whiplash at times.
  • Background Music Override: Unless you're playing the Sega CD or PC versions, the race with Metal Sonic uses the Bad Future theme even if you've achieved a Good Future for the Zone.
  • Bad Future: Trope Namer. The Good Future that Sonic's goal is to make inverts this.
  • Band Land: Stardust Speedway in the present. It becomes a Temple of Doom in the past and a futuristic city in the futures.
  • Bonus Stage Collectables: The Time Stones.
  • Boss-Only Level: The third acts in each zone only feature a short platforming section before the bosses. Collision Chaos and Stardust Speedway are the ones closest to this trope, as most of the first is Eggman's pinball arena and the latter focuses on a race against Metal Sonic.
  • Bottomless Pits: Almost entirely absent in this game, unlike just about every other Sonic game ever. Some exceptions:
    • One of the obstacles in Metallic Madness Zone 3 is a large bottomless pit with some tricky platforming above it.
    • There's also one in the Present stage of Stardust Speedway Zone 1 right before the end of the level. However, it's almost impossible to get down there and even if you do, there is still a way back up. You have to deliberately kill yourself to fall into that pit. There's also one in the Past of Stardust Speedway Zone 2. Like the example mentioned above, there is a short wall and spring blocking the drop, meaning you have to try to fall down there.
    • Changing time periods in an unexpected place in Palmtree Panic will sometimes cause you to de-warp in the middle of scenery. Usually, a little movement and jumping will cause you to glitch through the walls back into the stage proper (as the programmers clearly expected this to happen). On rare occasions, however, it will drop you below the stage, killing you.
  • Breaking the Fourth Wall: As usual, Sonic gets impatient if he's idle. Wait three minutes without pausing, and then he'll say, "I'm outta here!" and proceed to jump off the screen, netting you a Game Over regardless of how many lives you have left. He shoots you an angry glare the entire time. In the 2011 remake, Tails yawns at you as usual. However, he won't force the game to end after three minutes of idling.
  • Break Them by Talking: The Bad Future theme of Metallic Madness in the JP soundtrack attempts to do this to the player by featuring a robotic voice saying some demotivational words: "You can't do anything, so don't even try. Get some help. Don't do what Sonic does. ...Sonic, dead or alive, is m-m-mine!" This is an inversion of a line from the theme song "You Can Do Anything": "...'cause if you try, you can do anything!"
  • The Cameo: Tails shows up with the Tornado in the D.A. Garden and with a buggy in a secret artwork (captioned with "See you next game!"). For the 2011 remake, he is Promoted to Playable.
  • Chicken Walker: The first boss is this, with spiked feet and springs for fists that knock you backwards.
  • Comic Book Adaptation: In issues 26-28 of Sonic the Comic and issue 25 of the Archie comic.
  • Cosmetic Award: Destroying the Metal Sonic hologram projectors in the Past has no effect on the futures or the ending, but it does make some animals appear. The remake gives you a little more incentive to destroy them by tying it into an achievement/trophy.
  • Creator Cameo: Composer Naofumi Hataya has a small cameo in the JP soundtrack. He's the guy screaming in the background of Quartz Quadrant's Bad Future music.note 
  • Cyberpunk Is Techno: The JP soundtrack gives the present time period of the technologically advanced Wacky Workbench a fast-paced and chaotic techno tune.
  • Damsel in Distress: Amy/Rosy.
  • Darker and Edgier: In comparison to the Genesis titles, due to the presence of the Bad Futures.
  • Developer's Room: One of the cheat codes brings up a screen featuring the developers' time attack records.
  • Downer Ending: In The Stinger of the Bad Ending, there's a time rift, and Little Planet reappears, covered in its metal casing and chained once more, implying Eggman used the Time Stones to hit the Reset Button on his failure.
  • Dummied Out: "Round 2", which was, apparently, a ruins stage; a Special Stage, which can be accessed with a code; and some items. To fill in the void, "Desert Dazzle" was supposed to appear in the remake, but Sega declined the content and all that remains of it is a secret teaser picture. The rumored Final Fever level was scrapped again as well.
  • Easter Egg:
    • A statue in Wacky Workbench Zone 1,note  some artwork, and a Dummied Out Special Stage.
    • The Secret Sound Test in the original release contains a number of these. Entering the right combination of three (two in the PC / Gems Collection version) numbers will take you to several pieces of artwork, start a secret Special Stage, or unlock Debug Mode.
  • Eternal Engine: Metallic Madness and Wacky Workbench, as well as most of the Bad Future levels being combined with the current level trope. Wacky Workbench Good Future tones this down slightly, being more focused on toy imagery. Tidal Tempest is this in both futures, being a run down base in the Bad Future, while being an aquarium of some sort in the Good Future.
  • Ethereal Choir:
    • The Japanese final boss music has a woman singing in the background; there are no lyrics, so it's essentially a One-Woman Wail with instruments.
    • The Bad Future version of Tidal Tempest in the U.S. soundtrack has a chorus chant.
  • Evil Knockoff: Metal Sonic.
  • Expy:
    • According to Naoto Ohshima, most levels, with the exceptions of Quartz Quadrant and Wacky Workbench, were made as more surreal versions of the original Sonic the Hedgehog levels. Even the level theme order is the same. Sometimes, the similarities are subtle, sometimes not:
      • In Palmtree Panic, the Badnik "Kamemusi" looks like a Moto Bug and behaves like a Crabmeat.
      • Collision Chaos has a Spring Yard at the end of both Zones 1 and 2. The second zone also has two goals, just like Spring Yard Zone Act 2.
      • Tidal Tempest's graphics resemble Labyrinth's. The water current gimmick, which sends Sonic spinning underwater is used in the second zone.
      • Stardust Speedway shares its level theme and position with Star Light. It plays rather differently, though, besides being fast-paced.
      • Metallic Madness' spinning, disappearing and moving platforms and doors are all from Scrap Brain. There's also a Giant Mook version of the Bomb badnik called Bigbom and each Zone has a unique background, just like Scrap Brain.
      • Kama Kama/Robot Mantis, a Badnik in Collision Chaos based on Kama Killer/Slicer from Sonic 2, but with linear instead of homing projectiles.
    • The Time Stones clearly fill in for the Chaos Emeralds.
    • In addition, Quartz Quadrant and Wacky Workbench strongly resemble Hidden Palace Zone and Cyber City Zone, respectively. These levels were designed in the early stages of Sonic 2's development. However, they didn't make it into the final version (although elements from them did). It's quite possible that this was a conscious move, as Sonic 2's developers had to cut several levels due to a tight deadline.
  • Flower Motifs: The Badniks contain seeds which sprout into flowers, as opposed to the "animal battery" motif the series normally uses.
  • Game-Breaking Bug:
    • Move Sonic to behind the starting point (i.e. left of "0000") while using Debug Mode, and the game will crash. There is also a bug which stops the music from looping and the next level from loading should the player take too long.
    • Also, there's a point in the Past of Metallic Madness where you have to navigate some springs. The problem is that in the original versions of the game, you cannot reach the top platform. The only way around it is to try to get back to the present. If you can't, you are stuck. Extra platforms were added in the 2011 release to remedy this issue.
  • Gotta Kill Them All: You can get the good ending without beating any Special Stages by going to the Past in every Zone and destroying a unique machine, which also destroys all robots in the past. Doing so also lets you go to the Good Future in the same level.
  • Green Aesop: Yup, it's there. Pretty standard for early Sonic games.
    • Solar Punk: In the Bad Futures, it's notable that, because of Eggman taking over, the environment is more or less in a state of disrepair (including the robots themselves, amusingly); but in Good Futures, it's shown that nature and technology can indeed be in the same place without disastrous results. For example, the Good Future of Palmtree Panic is inhabited by small squirrels and has a system of pipes that regulate the clear water in the area, instead of spreading polluted water as in the Bad Future, with the water being pumped directly to the palm trees, which now have star-shaped decorations in the middle of the leaves. This is in stark contrast to most Green Aesops, which usually believe and preach that harmony between nature and machine cannot exist.
      • Further examples: the Good Future of Tidal Tempest looks like some sort of giant hydroponic greenhouse with nutrient-rich green water; in the Bad Future, the plants are dead or roboticized, and the water is magenta.
  • Guide Dang It:
    • For players trying to destroy all the robot transporters in the past, Wacky Workbench Zone 1's device is infamously difficult to reach on the first try. In order to reach the machine, you have to jump on top of a crushing piston near the level's end, which sends you down the pipe where the machine is located instead of killing you as with most crushing pistons in the series, such as Metropolis Zone's in Sonic the Hedgehog 2 and, incidentally, Metallic Madness in this game, which has them work as in most of the rest of the series. Fortunately, it's possible, albeit difficult without the skill and/or Save Scumming, to have all the Time Stones by this point for those who don't want to bother with the machine.
  • Hailfire Peaks: Common in this game, though it often only applies to the visuals:
  • Inconveniently Placed Conveyor Belt: Everywhere in Quartz Quadrant. In the past, they move fairly slowly, in the present they are average speed, and in either of the future stages, they move pretty damn fast, so getting past them can be a bit annoying. You can change the direction they go in, but it doesn't always help.
  • Impact Silhouette: Can happen in Palmtree Panic Zone 1 Present and Past if Sonic enters a tunnel in the middle of the level.
  • Improbable Aiming Skills: During the bad ending, just look at the trajectory that Sonic's rock makes as he throws it at Eggman.
  • Indecipherable Lyrics
    • The JP Metallic Madness Present theme has a verse which is pretty much unintelligible. The only parts that are understandable are "Get yourself ready for a fight" and what sounds like "Yo, we're outta here!"
    • Also from the JP soundtrack, the boss music can be hard to understand aside from the "Work that sucker to death! Come on now! Work that sucker to death!" chorus and the spoken part that describes the foregone conclusion of the boss himself not standing a chance.
  • Insistent Terminology:
    • Whoever's behind the terminology in the series decided that what most Sonic games call an Act, this game would call a Zone.
    • What are usually Zones in Sonic games are called "Rounds" here. "Act" is nowhere to be found anywhere.
  • Leitmotif: The JP boss music for Eggman, due to part of the lyrics:
    The war began. Earth trembled in fear. Bald, brainy, and cold-hearted. The distance grows closer, little by little. Wow! The power he possesses is incredible! He doesn't stand a chance!
  • The Juggernaut: Metal Sonic is completely invincible to Sonic's attacks thanks to an electrified force field he has, and his boost function allows him to effortlessly smash through obstacles Sonic has to work his way around. Sonic is only able to defeat him by using a combo of the closing goal gate of the race course they're on, with Robotnik's insta-kill laser finishing the job.
  • Loophole Abuse: Despite having a ten minute limit per act, it's possible to spend far more time than that in any one level. A successful time warp will revert the stage timer back down to five minutes. If you've been playing for less than five minutes, the timer will be unaffected. Also, if you're in Debug Mode, the timer doesn't seem to work at all. Just don't go too far to the left.
  • Lost Woods: Collision Chaos is a forest with a lot of mechanical elements thrown in.
  • Macro Zone: Some of the end of Metallic Madness Zone 2 where Sonic goes tiny. He still retains normal jump height though.
  • Missing Secret: For those who aim for 100% completion, Metallic Madness can be puzzling at first when it comes to finding Metal Sonic projectors. In fact, it doesn't have any. This makes sense since he was defeated in the previous Zone (albeit in the future).
  • Mondegreen: The music with lyrics, which is several tracks except for past music, may end up getting misinterpreted since it was made for older hardware. For example, look up the JP boss music on YouTube and see how many people hear the lyric "Work that sucker to death" incorrectly, with mishearings such as "Work that toaster to death" and "Work that son of a bitch."
  • Mook Promotion: The "hotaru" Badnik from Stardust Speedway later shows up as the mid-boss before the final boss.
  • New Jack Swing: This game, alongside Sonic 3 & Knuckles, is one of two "Classic" era games to have its soundtrack heavily influenced by the genre.
  • No Fair Cheating: In the remake, activating Debug Mode disables achievements, and Zone times won't be recorded.
  • No Name Given: With the exception of Metal Sonic and Palmtree Panic's boss, EGG-HVC-001, the bosses lack names. One piece of concept art shown in Sonic Generations, however, includes an early design of the final boss with the label "Psyco-Egg".
  • Non-Indicative Name: If the name of a Round refers to a background element rather than a gameplay mechanic, chances are it's completely absent in its Bad Future. Palmtree Panic's Bad Future has all of its palm trees replaced with machines, Quartz Quadrant's Bad Future has been mined bare of its quartz, and a thunderstorm hangs permanently over Stardust Speedway's Bad Future, blocking all of the stars.
  • No OSHA Compliance:
    • Wacky Workbench, a factory where the ground floor bounces things high up into the air at random intervals (or constantly in the Futures).
    • Quartz Quadrant wouldn't fit OSHA standards either with spikes everywhere.
  • Non Standard Game Over: Put the controller down. Three minutes and one "I'm outta here!" later...
  • One-Hit Kill: Eggman's pacing laser in Stardust Speedway Zone 3 is an instant kill even if you have Rings.
  • Our Founder: The statues of Eggman at Wacky Workbench and Stardust Speedway (Present and Bad Future), and the image on the mountain that appears in the opening (unfortunately, the close-up of the mountain tends to be cut in the re-releases).
  • Oxygenated Underwater Bubbles: Present throughout Tidal Tempest. Eggman uses them as a shield in that level's boss that you can breathe through and attack him for a One-Hit KO.
  • Palmtree Panic: Trope Namer.
  • Painting the Medium: The Present and Future music tracks are in Red Book audio (i.e. standard Compact Disc Digital Audio, or CDDA), while the Past songs are in the lower quality PCM format used by the Sega CD's PCM chip.
  • Pinball Zone: Collision Chaos.
  • Platform Hell: Wacky Workbench 1 is unique - and controversial - among Sonic levels for its heavy focus on platforming. There is generally a straightfoward single path to the goal, but falling off the platforms will cause Sonic to land on a powerful bouncy floor that sends him towards the closed-off top areas, from where the player must fall back and try again.
  • Precocious Crush: A lot of people forget that Amy Rose was introduced as eight years old - the same age as Tails in Sonic the Hedgehog 2. In fairness, some sources state that she was aged up in her redesign to be closer to Sonic.
  • Press X to Die: In the Sega CD (but not Mega CD) version, pressing one of the jump buttons while the game is paused will restart the level at the cost of one life provided you have at least two lives available. Otherwise, this reverts the player back to the title screen. This also works in the PC version.
  • Promoted to Playable: Tails is unlocked in the 2011 remake just by beating the game once as Sonic. He actually makes the game easier due to his ability to fly and swim (taken from Sonic 3), which raises the question of why they didn't have him there from the start for inexperienced players. As a tradeoff for the easier difficulty, you can't earn Achievements while using Tails.
  • Puzzle Boss: Many more compared to the rest of the series; while most of the bosses are of the "hit until he's dead" variety, all of them except the first (and, eventually, the last, which gets progressively easier to hit as the battle progresses) also require that you figure the "trick" to hurting them, from manipulative platforming to whittling down shields bit by bit.
  • Refrain from Assuming: "Sonic - You Can Do Anything", the opening theme song from the JP version, is often incorrectly cited as "Toot Toot Sonic Warrior" after part of the chorus, despite "you can do anything" actually being lyrics.
  • Real Men Wear Pink: For no clear reason, the EGG-HVC-001 is colored pink in the Good Future of Palmtree Panic.
  • Remixed Level: Every Zone in the game has four versions of itself for each time period, including the two futures separately. Each of these four versions have minor changes to the layout, though the requirement to take alternate paths is rare due to the nature of this game's time traveling.
  • Reset Button: The bad ending. Eggman presumably uses the Time Stones to revert everything you did in the game.
  • Sampling:
    • The lyrics "Work that sucker to death! Come on, now! Work that sucker to death!" come from Xavier's song "Work That Sucker to Death". Worthy of note is that although the original song did say "work that sucker to death" often, this particular sample is only the chorus to the JP Sonic CD boss music.
    • The JP soundtrack samples its opening and ending themes during normal gameplay, with the game over theme sampling the former, albeit slowed down and muffled, and the stage clear theme sampling the latter. Interestingly, both are intact in the 2011 remake despite the lyrics being cut from their sources.
  • San Dimas Time: With all of the time travel involved, the game still has the 10-minute-limit in its stages. Going to the past, or future (Good or Bad), doesn't change this in the slightest.
  • Save the Princess: While the rascally pink hedgehog was named "Amy" in the European Mega CD manual, she was renamed "Princess Sally" in the North American Sega CD manual, presumably to tie into the cartoon she hails from. This was quietly reverted in re-releases and quickly forgotten (likewise for Rosy the Rascal).
  • Save Scumming: The 2011 version of the game makes a save at the beginning of a Special Stage and doesn't save the results if the game is restarted before the results screen finishes. This makes it easier to get all seven Time Stones early, and doing it early enough would mean Quartz Quadrant Zone 2 and on automatically have Good Futures.
  • Scenery Porn: The environments are beautiful to look at, possessing a dream like quality to them. This especially holds true for the Good Futures, a mix of technology and nature in bright flashy colors.
    • Scenery Gorn: The Bad Futures. Eggman's corruption hasn't been fixed, and the world has become a nightmarish dystopia. It's especially bad for the levels where water can been seen; the water ends up looking horribly polluted and nasty.
  • Science Is Bad: The Bad Futures, with all the broken machinery throughout them. Even Eggman's Mecha-Mooks and his own base are broken and rusted with neglected ruin.
    • Inverted in the Good Futures, which also have a lot of machinery in them.
  • Screw This, I'm Outta Here!: If the player doesn't move Sonic for three minutes, Sonic will say this word for word (excluding screw this) and ditch the player by jumping off the stage, resulting in a Non Standard Game Over.
  • Scripted Event: A rare story instance of this in a classic Sonic game. When you first arrive at Collision Chaos, you find Amy chasing you around and that the tunnel to the rest of the level is blocked off by some spikes (there's a ledge nearby, but that gets you nowhere either). Cue Metal Sonic arriving, smashing through the spikes, kidnapping Amy and flying off. Even if you use debug mode to skip this part, it's impossible to save Amy—Metal Sonic is completely immune to your attacks and will always grab her, fly off and vanish right away.
  • Set Right What Once Went Wrong: Sonic's goal is to save the Little Planet's future by ridding it of Eggman's influence. He can achieve this by destroying the robot transporter in the past or collecting every Time Stone.
  • Shielded Core Boss: The bosses in this game generally take fewer hits to trash. They make up for this, however, by having better / more devious defenses than usual, or by only being possible to beat in a non-traditional manner.
  • Shout-Out: Several in the 2011 remake.
    • The achievement for traveling through time at least once is "88 Miles per Hour".
    • The achievement for finishing any level in the Good Future is "Paradise Found".
    • The "King of the Rings" achievement is a reference to an old obscure Sonic song.
    • DJ Eggman wears a Jamaican headpiece on the Soundtrack Select screen.
  • Sliding Scale of Shiny Versus Gritty: The contrast between the good and bad futures.
  • Smashing Hallway Traps of Doom: Real ones are found in Metallic Madness. Earlier, objects that look almost identical to these are found in Wacky Workbench, but they are completely harmless and actually drop you into secret areas if you stand on them as they slam into the ceiling. This is necessary to reach one of the robot transporters.
  • Solar Punk: Traveling back to the Past and destroying the robot generators found in the first two Zones of each Round will prevent the Bad Future where the environment is converted into a Polluted Wasteland, and create a new timeline where widespread technology works in harmony with nature to create a vibrant and colorful Good Future devoid of enemy robots.
  • Soundtrack Dissonance: The US boss theme ends up being this in the Good Futures. Wacky Workbench's Good Future also falls into this, having more emphasis on work tools in the background despite the zone being turned into a toy land.
  • Speed Run: The first game in the series to feature a Time Attack mode. This is also how you unlock some of the extras.
  • The Spiny: The "Kemusi" Badnik is an expy of Caterkiller from the original Sonic the Hedgehog, and Noro Noro, from the same Round, will also occasionally show spikes on its back.
  • Stealth Pun: The reason levels in this game are called Zones instead of Acts? That's because this game is (about) time travels.note 
  • Stepping Stones in the Sky: In the intro movie, Sonic used the falling debris of the Little Planet as platforms to reach it.
  • Super Title 64 Advance: Sonic CD for the Sega CD.
  • Take That: The name of the first boss is the EGG-HVC-001. HVC-001 was the serial number name of Nintendo's own Famicom console. As a bonus stealth insult, the HVC-001 is the easiest boss in the entire game. Fighting it in the Good Future also colors it pink, and this is probably the only explanation for that.
  • Tagline: The page quote.
  • Techno Wreckage: The Bad Futures. Wacky Workbench and Metallic Madness especially.
  • Temple of Doom: Stardust Speedway in the past is a Roman/Greek style city.
  • Theme Tune Cameo: "Sonic - You Can Do Anything" is an updated version of the Green Hills Zone music from the Sega Master System and Game Gear versions of Sonic the Hedgehog 2.
    • Speaking of which, the JP Game Over theme actually samples the vocals from the chorus of "You Can Do Anything" (the "Toot Toot Sonic Warrior" part) and slows them down.
  • Time Travel: A present mechanic of the game, inspired by various books and films, including Back to the Future.
  • Toy Time: Wacky Workbench's Good Future.
  • Tube Travel: A lot of it in Metallic Madness Zone 2. Tidal Tempest Zone 1 and Wacky Workbench also have a little of it.
  • Under the Sea: Tidal Tempest is an underwater area in the present and futures.
  • Underwater Ruins: Tidal Tempest, though oddly not in the past (it's just a partially-submerged cave).
  • Unique Enemy: The Taga Taga enemy found in Tidal Tempest also appears in Palmtree Panic, where it jumps out of waterfalls like Chopper from Sonic the Hedgehog, but this version rare enough that you won't meet it unless you explore.
  • Unlockable Content: The Special Stages in Time Attack, the D.A. Garden (the incomplete Sound Test, plus an image of the Little Planet) and the Visual Mode (the Video Gallery).
  • Violation of Common Sense: The fake Smashing Hallway Traps of Doom of Wacky Workbench. Standing on one will take you somewhere. One is required to go to the robot transporter in Zone 1.
  • Warm-Up Boss: Palmtree Panic's boss, the EGG-HVC-001, is a slow moving mini-mecha that can't even directly attack you; its only defense is two arms with easily dodgeable Bumpers attached, and otherwise its only "attack" is inflicting collision damage, and it loses an arm with two of the three hits it takes to mow it down, which can be easily done in less than 15 seconds—or if you want to be even quicker, you can just move right behind the boss and attack it directly from behind as soon as it lands (and it can't turn around to retaliate). On top of all that, due to an invincibility box at the beginning of the level, you can actually defeat the boss without being in any danger at all of being hurt. It's easier than Drill Eggman.
  • A Winner Is You: Finish the game with the good ending, or watch the good ending through Visual Mode. A screen will show up telling you that "YOU ARE GREATEST PLAYER", and Sonic, Amy and Metal Sonic will run across the screen from time to time. This screen was removed in re-releases.
    • The Tails ending in the remake is probably even more this because all you get is some explosions and then a credits roll. You do not even get a congratulations. At the very least, the credits for Tails are of the staff who worked on the remake, but it's still kind of disappointing.
  • Zonk: Though Bad Futures being interesting levels is a consolation, Future signposts largely exist to distract and roadblock the player from their true objective of fixing the Past. Especially later, accidentally going to a Bad Future at any point in a level can result in being unable to get back to a point where the Past objectives (or even Past Signposts at all) can be reached. As the game goes on, they start being placed in more and more devilish locations, such as just before or after a segment in which is it difficult to stop running, or right after spinning a Past signpost (which are used up after being hit), punishing careless or unobservant players. Once you get all the Time Stones though, you can warp straight to the Good Future instead.

Alternative Title(s): Sonic CD, Sonic The Hedgehog CD