Sonic, meanwhile, is on his way to Never Lake, completely unaware of Eggman's latest ambition. Our blue hero arrives on the shores of the lake and is shocked to see the legendary Little Planet chained to the local terrain. It doesn't take him three guesses to figure out the perpetrator of this deed, so he dashes up one of the chains to free the planet and throw a wrench into his rival's latest scheme. Unfortunately, Eggman has been clued in to his enemy's arrival, and preparations have already been made.

   Meanwhile, a young girl hedgehog named Amy Rose (aka Rosy the Rascal) is lured to Little Planet by a card reading that told her of a destined encounter with Sonic. Once there, Amy becomes the perfect target for Eggman to make sure he's got Sonic's attention and to show off his latest, most sophisticated creation to date: Metal Sonic. This robot duplicate of our hedgehog hero was designed to match Sonic's every move and even surpass his own namesake speed. This deadly new rival kidnaps Amy in front of Sonic's very eyes and escapes with his prize to Eggman's base.

   Sonic CD offers an interesting variation on the traditional Sonic formula. While the basic mechanics are the same, the tuning, direction, and overall structure is quite a departure from Sonics 1-3. Sonic's control is stiffer and more precise, a variable which reflects in the level design, which seems to be busier and with more emphasis on navigating small areas - a significant change from the broad, flowing style of other games in the series.

   Sonic's got his usual running and spinning maneuvers, sans the recently-introduced Spin Dash. Its replacement is a slightly more versatile (if somewhat clunkier) Dash maneuver:

	walk -- Push left or right on the D-pad to initiate Sonic's movement in either direction. As you hold the button down, Sonic gains speed.
	run -- Begin walking and hold down the button to make Sonic gain speed. After a few seconds, he'll break into a run.
	screech -- While running, quickly press and hold the opposite direction on the D-pad to make Sonic screech to a halt. He'll skid for a short distance, based on how fast he was moving.
	look up -- While standing still, press up on the D-pad to make Sonic gaze to the heavens. Tap up on the D-pad twice quickly to have the camera pan upward, giving you a view of Sonic's overhead surroundings.
	crouch -- While standing still, press down on the D-pad to make Sonic duck. Tap down on the D-pad twice quickly to have the camera pan downward, giving you a view of the stage beneath where Sonic stands.
	spin (回転) -- While moving, press down on the D-pad to make Sonic curl into a rolling attack. He'll remain in this position until you jump or slow down. The speed of Sonic's movement while in spin form is based on how fast you're moving when you launch it, and also on the terrain Sonic rolls along.
	spin jump (回転ジャンプ) -- Press A, B, or C at any time to make Sonic leap into the air with a spin attack. The height of the jump is proportional to how long you hold the button down.
	push -- There is actually nothing to push in Sonic CD. However, that won't stop Sonic from trying everytime he runs up against a solid object.
	Dash (ダッシュ) -- While standing still, press up and hold A, B, or C to have Sonic rev up with a figure 8. When he gains enough momentum, release the D-pad to have him dash off at maximum speed. (The only other way to achieve this speed is to bounce off of a horizontal red spring.) A rolling version of the Dash maneuver can be performed by holding A, B, or C while crouching.
	hang -- Sonic automatically latches on to the horizontal bars in Wacky Workbench. Slide him along by pressing left or right on the D-pad, and let go by pressing A, B, or C.

   The basic assortment of Sonicy items is present and accounted for, along with a couple of new gadgets to make time travel as quick and easy as a walk to the park:

	Ring (リング) -- As long as Sonic has some of these, he won't lose a life if he takes damage. You get an extra life for every 100 you collect and each one is worth 100 points at the end-of-Zone score tally.
	Item Box (アイテムボックス) -- In each stage, you'll find a number of these power-up bearing monitors. Pop them open with a spin to procure one of five power-ups: Ring 10 (リング10) - Worth 10 Rings Barrier (バリア) - Absorbs one hit High Speed (ハイスピード) - Temporary speed increase Muteki (無敵) - Temporary invincibility 1up - Gives Sonic an extra chance. (1ups can also be earned by scoring 50,000 points.)
	Sai Start Marker (再スタート・マーカー) -- These hold your place in a stage: should you lose a life, you'll start back at the last Start Marker you crossed.
	Bobbin (ボビン) -- Round bumpers found only in Collision Chaos. Bounce off one for 100 points, up to 5 times for a total of 500 points. (They stop dispensing points after the fifth hit.)
	breakaway bumper -- These frog egg looking things shatter as soon as Sonic smacks into them. They're worth 100 points each, and are found only in Collision Chaos.
	spring -- Leap onto the broad side to catapult Sonic into the air. The yellow ones send him flying a short distance and the more powerful red ones send him farther.
	spikes -- Don't touch the pointy side, stupid. Sometimes they're just lying out in the open, and sometimes they pop in and out of the ground (or the ceiling, or the walls).
	switch -- Jump on the button to cause a change in the nearby scenery, usually necessary to proceed.
	air bubbles -- Large, oxygen-filled bubbles periodically rise from these clusters: tag one to fill Sonic's lungs with air and prolong the time you can spend underwater.
	time warp plate -- Cross a plate to spin it around, rendering it useless for the rest of the stage. Once the sign has been flipped, a Warp Panel indicating its destination (past or future) will appear in the lower left-hand corner of the screen. With the Warp Panel active, start running. Once you've attained max speed, a trail of stars will appear behind Sonic and the Panel will begin flashing. Should you lose speed or come to a stop during this phase, you'll blow the warp and the Panel will disappear. If you're able to hold max speed for about three seconds, you'll warp to the destination time zone. (For example: if you're in the present and you spin a "Past" sign, you'll be warped to the past. If you're in the past and you spin a "Future" sign, you'll be warped to the present.)
	Eggman's machine -- There's one of these in the past of every Zone. Destroy it with a spin to free the future of that Zone and score a sweet 1,500 points in the process.
	Metal Sonic projector -- Metal Sonic harasses the local wildlife as portrayed in this hologram: one appears in the past of every Zone. Destroy it and animals will prance happily about the stage.
	bonus plate -- These signs can be found at the end of each first and second Zone. Cross them to end the stage.
	Special Stage ring -- These giant Rings only appear above bonus plates when you cross with at least 50 Rings on-hand. Jump in to warp to the Special Stage. (Once you've collected all 7 Time Stones, the Special Stage rings no longer appear.)
	capsule -- These are found at the end of each third Zone, after facing the boss. Pop it open with a spin to unleash a shower of dancing flowers upon the unsuspecting earth.

   Eggman's gone on an entomological kick with his latest crop of robo baddies. He also seems to have been lax in their maintenance, because enemies will appear in various states of disrepair based on the time zone: enemies in the past are all new and fully functional, enemies in the present consist of both working and busted bots, and enemies in the future are all old and damaged. Broken enemies lack some method of offense or mobility that their more well-kept brethren possess, but in general they attack with the same patterns and they're all worth the same points. Interestingly, there are no happy critters to free by busting bots this time. All you get is a magical seed that falls and immediately blossoms into a jagged, dancing flower, which stands as a monument to your victory. (Unfortunately, the Sonic CD instruction manual only lists a few enemies, so most of the official names are unknown.)

	Mosqui (モスキー) -- Kamikaze mosquito bots that fly in a straight line, but immediately nose down and jam their pointy nasal units into the ground as soon as Sonic passes underneath. The damaged ones fly a bit slower.
	Patabata (パタバタ) -- Butterfly bots that flutter around in a zig-zag motion. The damaged ones fly slower.
	Anton (アントン) -- Unicycled ant bots that roll back and forth along the ground. The damaged ones simply look rather depressed, and putter along slower than their more cheerful brethren.
	??? -- Beetle bots that roll back and forth along the ground, pausing occasionally to fire a pair of flashing projectiles from their ass ends. The damaged ones (which don't look any different) roll slower and, though they put forth a valiant effort, are incapable of firing projectiles.
	Taga-taga (タガタガ) -- Unidentifiable crustacean bots that hop in and out of waterfalls, ala Bata-bata. They have no broken form.
	??? -- Cicada bots that hang around on walls, then fly off in a zig-zag pattern as Sonic approaches. The functional ones leave little trails of harmless sparkle dust while the damaged ones do not.
	??? -- Ladybug bots that hover along the ground and slowly fly away as Sonic approaches. As they retreat, they drop mines that explode after a few seconds. The damaged ones don't drop bomb turds.
	Kama-kama (カマカマ) -- Mantis bots that roll along the ground and fling their sickle-like arms at Sonic. The blades can be deflected with a spin, leaving Kama-kama helpless. ("Kamakiri" is Japanese for mantis.)
	??? -- Dragonfly bots that fly around over a small area. The damaged ones move slower.
	Taga-taga (タガタガ) -- This version of Taga-taga swims in a straight line from left to right. As Sonic approaches, he'll fire off the three spikes on his back, then dash away. The damaged version doesn't have the three spikes to begin with, so he just kind of putters back and forth helplessly.
	??? -- Water strider bots that glide along the surface of the water and fire flashing projectiles. The damaged ones glide slower and have no projectiles to fire.
	??? -- Crayfish bots that swim along the sea floor very slowly, then suddenly lunge toward Sonic as soon as he approaches. The damaged ones just kind of hop...
	Kumo-kumo (クモクモ) -- Springy spider bots that can't move along the ground, but leap high into the air. As they leap, they fire a web of sticky gunk onto the ground: run into it and Sonic becomes momentarily stuck. The broken ones don't leap as high and can't sling web. ("Kumo" is Japanese for spider.)
	Sasori (サーソリー) -- Scorpion bots that roll along the ground and fire laster shots from their tails. The damaged ones move slower and don't have tail lasers. ("Sasori" is Japanese for scorpion.)
	??? -- Caterpillar bots reminescent of Nal. They squirm slowly along the ground and can only be damaged on their spikeless noggins. Hit them anywhere else and Sonic takes damage. The broken ones are totally spike-free, and can be smacked anywhere you please.
	Noro-noro (ノロノロ) -- Snail bots that squirm slowly along the ground. Spikes occasionally thrust out from their shells, and it goes without saying that you should not attempt an overhead assault at this moment. The damaged ones lack the built-in spike trap. ("Noro-noro" is Japanese for slow or sluggish.)
	Pohbee (ポービー) -- Chunky bee bots based on Beeton. They fly through the air and fire flashing projectiles. The damages ones fly slower and can't shoot.
	Batapyon (バタピョン) -- Grasshopper bots that spring around gleefully. The damaged ones spring slower and not so gleefully. ("Batta" is Japanese for grasshopper while "pyon-pyon" means hop.)
	??? -- Cicada bots that hang out on the wall and fly away when approached, dropping bombs in their wake. The damaged ones ain't got no bombs to drop.
	??? -- Grub-like bots that hide in overhangs and drop down as Sonic approaches. After a few moments they sprout spikes, then zip back into their hiding place. The damaged ones are spikeless.
	??? -- Bizarre winged bots that fly spiral patterns in and out of the background. You can only make physical contact when they're on the same plane as Sonic. The damaged ones fly slower.
	??? -- Creepy chick-looking bot that flies around the air with a trail of ghost images. If Sonic approaches, it'll fire a ghost image in his direction. The damaged ones look the same, but fly slower and lack the ability to sling ghosts.
	??? -- Pillbug enemies that crawl slowly along the ground, but curl up into a speedy roll as soon as Sonic approaches. These guys have no damaged form.
	??? -- Lightbulb bugs that always fly in pairs: as soon as Sonic approaches, they lock themselves into position above and below, then fire an electric jolt between. Once their attack is spent, they fly away. The damaged ones try the shock treatment, but don't succeed at anything more than a harmless flash.
	Mechabu (メカブ) -- Kabutomushi beetle bots with razor wheel schnozzes. They roll slowly along the ground, raising and lowering their buzz saw helmets, but they never turn around. The damaged ones look the same, but can't move their blades.
	??? -- These grabby bots won't damage Sonic if they get hold of him, but they'll force him into his spin posture and send him rolling into whatever dangers may lie beyond. Occasionally they carry Item Boxes. The damaged ones look the same, but move slower.
	Pohbee (ポービー) -- This version of Pohbee lugs swinging dual maces. The damaged ones look the same, except they fly slower and only swing a single mace.
	??? -- Walking bomb bots that are like Bomb, but much larger. As soon as Sonic approaches, they follow (very, very quickly) and self-destruct into a shower of flashing projectiles. They can't be damaged, only avoided.
	??? -- Pillbug bots identical to the ones from Stardust Speedway save color. Damaged ones roll slower.

   There are a total of 7 Rounds each with three Zones. New to the mix is time travel - each Round has 4 different visual schemes with slight variations in level structure:

• Present -- Sonic begins each Zone in the present. You can play straight through or pop into another time period for a visual change and the opportunity to free the future of Eggman's menacing grip. Some of the enemies here have broken down and lost abilities with age, but some are still fully functional.
• Past -- The stage as it was in times past. Eggman's already been here and has left a single robot machine in each Zone: destroy it to enable the good future scenario for the stage, instantly eliminating all enemies in the past and reducing the number of enemies in the present. You might also keep an eye open for the Metal Sonic hologram: he's usually harassing the local wildlife. Destroy the projector and the liberated critters will frolick happily around the Zone. Note that enemies here are all in perfect working order, so they're a nasty bunch.
• Future -- The default future for each stage, long since conquered by Eggman. Zone 3, the boss round, always takes place in the future: if you freed the futures of Zone 1 and 2, Zone 3 will revert to the good future. If you neglected your time travelling duties, it will be the default bad future. Enemies here are old and broken down, so they aren't much to worry about.
• Good Future -- This future is clean and bright, freed from Eggman's control. There are no enemies to be seen and animals prance happily about the scenery. To achieve this lovely scenario, head into the past and destroy the robot machine. (Note that if you manage to collect all 7 Time Stones, subsequent futures will automatically be converted to good futures. Furthermore, if you free the future in every Zone of every Round, you will get the good ending regardless of whether or not you collected all 7 Time Stones.)

   Each third Zone entails a boss fight preceded by a small stretch of platforming, usually just enough to grab some Rings for the impending battle. Bosses are very different from other games in the series: Eggman's contraptions only take a few spins a piece (usually 3), but even landing a hit can be tricky as they've got some particularly well thought-out defense systems.

Palmtree Panic -- This series requisite tropical paradise offers the first opportunity to observe one of Sonic CD's graphical quirks: climb high enough on the map and the background flips. The vertical ramps are a good place to check this out. Donut platforms react differently based on time zone: in the present, they're invisible until you stand on them; in the past, they're always visible; and in the future, they fall out from under you. Amy Rose is waiting at the end of Zone 1 present: if she grabs hold of Sonic, she won't let go. Jump to evade her wicked grasp of temptation. Boss: Eggman attacks in his EGG-HVC-D01, a mech walker armed with spiked shoesies and bumper hands that act as shields. As he prepares to charge, the Doc briefly retracts his hands: this is the only opportunity to attack. A bumper falls off after each hit, lowering the walker's defenses as the battle progresses.

Collision Chaos -- This bizarre pinball world defies description. At the beginning of Zone 1, Metal Sonic makes off with Amy, the metallic pervert. Press A, B, or C to trigger flippers and send Sonic flying. Smack into bumpers for 100 points a wallop, up to 5 times for a total of 500 points. Breakaway targets are worth 100 points each. Zone 1 features 2 possible exits. Boss: Eggman's hanging around at the top of a pinball arena and your job is simply to bounce, bump, and flip your way up to him. He drops mines to slow you down, but once you've made it to the top, just jump and hit him three times.

Tidal Tempest -- The underwater ruins form a labyrinth of pipes and caverns. As usual, stay underwater for too long and a countdown appears above Sonic's drowning head. Fail to reach the surface or find an air bubble before the timer runs out and you lose a life. Jump on switches to make those pesky walls move out of your way. It's impossible to fight currents, so when you get caught up in a riptide, go with the flow. Boss: Eggman retreats through an endless maze: chase him down and smack him 4 times. He'll escape to an underwater arena where he syphons air bubbles from the ground and uses them as a barrier. Inhale enough bubbles to breach Eggman's defense, but watch for flashing projectiles: they can be tricky to avoid underwater. One more hit and Eggman's all wet.

Quartz Quadrant -- A large-scale mining operation is in progress in these crystal-rich caverns. Flip switches to reverse the flow of conveyor belts. Watch for falling rocks and stalactites. Boss: Eggman cowers in a giant piston above a conveyor belt. The Doc's only attack is to drop mines from the top of the screen: when the mines hit the ground, they shatter into 4 pieces each. Eggman can't be damaged directly, so the object is to run against the flow of the conveyor belt: as Sonic jets along, the belt picks up speed and brushes against the bottom of the piston. After a while, Eggman's tender tootsies will no longer be able to stand the heat caused by the friction, so he'll run off leaving the piston to explode behind him.

Wacky Workbench -- This towering factory features a springy floor: touch the tiles while they're flashing (which is most of the time) and you'll be catapulted high into the air where most of the action takes place along moving platforms. Electrical conduits weave through the background: don't touch them when they're lit unless you're in the mood for fried hedgehog. A small alcove near the beginning of Zone 1 past conceals a goddess statue: approach it and Rings spout from the sculpture's hands. In the future, the statue is replaced with a golden Eggman memorial. Destroy it and a brief shower of mines drops from the ceiling. Boss: Eggman makes his escape through a vertical arena with three layers. In the first room, hit him once and he dashes upward, breaking through the ceiling above. Four chunks of debris fall from the top of the screen: don't let 'em smush you, but jump on top of one. The floor charges with electricity that sends the four chunks of debris catapulting into the air: the object is to leap through the ceiling to the layer above, but your weight will slow the chunk you're standing on, so you need to jump to another one in midair to attain enough height. Repeat this process two more times. By the third round, spikes fall from the ceiling along with the shrapnel.

Stardust Speedway -- A giant golden Eggman statue is under construction at the center of this starry city. Head to the past to discover that a towering cathedral originally stood at the site: free the future and the cathedral evolves into an ostentatious neo-gothic skyscraper. Winding aerial highways make this the fastest stage in the game. Boss: Sonic finally confronts his metallic counterpart for a race, but of course the chrome clone isn't going to play fair: he can fly and tear right through obstacles Sonic would have to jump over or otherwise avoid. If you do manage to pull into the lead, Metal charges up with electricity and nails you from behind. Eggman trails behind the racers and tears up the highway with a powerful laser beam, so there's nowhere to run but forward. Beat Metal Sonic to the goal and he slams headlong into the gate just as it closes. With his new baby smashed to pieces, Eggman makes a run for it, leaving the bound Amy Rose behind. Free the damsel and there's only line of business left to attend...

Metallic Madness -- Eggman's factory is rife with giant buzzsaws, steep bank platforms and other sharp-edged objects ideal for preparing julienne hedgehog. Zone 2 is a complex labyrinth of chutes: make it to the end and Sonic passes through a shrinking laser that reduces him down to his continue sprite. Navigate a micro-sized tunnel to be reverted to normal proportions before crossing the goal. The final boss chamber is guarded by a trio of camouflaged lightbulb bots: they jet around the arena and make themselves visible just long enough to fire a laser into the ground. Boss: Eggman's final machine is simple enough: a large spherical hovercraft with four panels circling the exterior. The trick is to reach between the panels to land a hit. Each time Eggman takes damage, one of the panels falls off and his method of attack changes. In the first two rounds, he lowers himself to the ground and rolls across the floor. He then flies just out of reach and flings the panels into the air: the slabs rain back down from the ceiling and fall narrow-side out at random points on the ground. Finally, he homes in on Sonic and stretches the panels outward for a damage-inflicting probe. Once 2 panels have been destroyed Eggman abandons the rolling attack, but still probes and flings off his remaining 2 panels which fall broad-side out onto the floor. When he's down to a single panel, the villainous doctor abandons the probing attack, but when he flings off his only remaining panel, it flies onto the arena broad-side out at a long angle, making it difficult to avoid. He also uses the last panel as a pogo to hop across the floor. Land one more hit (for a total of 4) to finish the job.

   If all that running back and forth between time zones is too much hassle but you still want the good ending, you could opt to shoot for the seven Time Stones. To get a chance at a Time Stone, get to the end of any Zone (barring boss stages) with at least 50 Rings on hand. Leap into the giant Ring hovering above the bonus plate to be warped away to the Special Stage.

   Sonic trots along a flat, square field that scrolls and rotates in F-Zero fashion - a unique sprite enhancement trick added to the Mega-CD's graphics library specifically to compete with the Super Famicom's popular Mode 7. Sonic canters forward automatically, gaining speed as he runs: your only job is to steer him in the right direction and press A, B, or C to jump when necessary. The object is to destroy all 6 UFO's within the time limit.

   Sonic CD sports a flash save feature that lets you continue from the Zone you left off at even if the system's been powered off. Unfortunately, it only holds one game at a time, so if you start a new game, your old save is erased. In addition to the scenario game, there are a few extra modes to unlock:

• Time Attack - Lets you race the clock in Zones and Special Stages you've cleared in the main game. Only the present version of each Zone is playable, and there are no time warp plates. Get one of the three high scores for the prestige of having your initials on the record screen. If you've got the highest number of initials on the board, you get a special screen after completing the scenario game: it features Sonic, Amy, and Metal Sonic running around whilst numerous animals frolick happily along with the text: "Congratulations [initials]! You are greatest player!"
• D.A. Garden - Get enough high scores in Time Attack to unlock this mode, an elaborate sound test that gives you control of the Little Planet while listening to your favorite BGM. You can zoom in, out, or alter the rotation of the planet.
• Visual Mode - Get even more high scores to unlock this mode, which lets you view the game's anime intro and both endings at your whim. It also includes a "pencil test" animation of the incomplete movies.

   In the original ending animation, the music doesn't begin until the credits start rolling. The animation itself features sound effects. In the US version, the music begins as soon as the animation starts and there are no sound effects. Additionally, the credit roll is a bit longer as it includes credits for the US score.

   The US manual fudges the story around just a bit (less than usual) and refers to Amy Rose as "Princess Sally". This was evidently an effort on Sega's part to tie-in with the Sonic comics and cartoons of the era, which featured a (totally different) Princess Sally as one of the main characters.

• Mega-CD: At the title screen, press: B.
• PC: At the title screen, press: SPACE.

Pro scores:

• Mega-CD: At the title screen, press: C.
• PC: At the title screen, press: SPACE.

Sound test:

• Mega-CD: At the title screen, press: A.
• PC: At the title screen, press: SPACE.

Debug mode:

• Mega-CD: Input the sound test code and adjust the numbers to read: FM#40, PCM#12, DA#11, then press START. A picture of Tails will appear along with the text "See You Next Game -- Judy Totoya". ("Judy Totoya" is a pen name for Yasushi Yamaguchi, Tails' original designer. He worked on the Special Stages in Sonic CD.)
     A = Changes highlighted item
     B = Toggles between items and Sonic
     C = Places highlighted item
  
• PC: Input the sound test code and adjust the numbers to read: PCM#12, DA#11, then hit SPACE.

Secret Special Stage:

• Mega-CD: Input the sound test code and adjust the numbers to read: FM#07, PCM#07, DA#07, then press START.
• PC: Input the sound test code and adjust the numbers to read: PCM#07, DA#07.

Art screens:

• Mega-CD: To access these hidden graphics, input the sound test code and adjust the numbers:
     MC Sonic: FM#42, PCM#03, DA#01
     Sega forever: FM#46, PCM#12, DA#25
     Demonic Sonic: FM#42, PCM#04, DA#21
     ゆ-あ-く-る: FM#44, PCM#11, DA#09
  
• PC: To access these hidden graphics, input the sound test code and adjust the numbers:
     MC Sonic: PCM#03, DA#01
     Demonic Sonic: PCM#04, DA#21
     Sega Forever: PCM#12, DA#25
     ゆ-あ-く-る: PCM#11, DA#09
  

I'm outta here!: At any point in any Zone, leave Sonic standing perfectly still (don't pause the game). After three minutes, he'll say: "I'm outta here!" and leap off the screen. This ends your game...

   The character Amy Rose was probably derived from the like-named Amy, Sonic's girlfriend from the Shogakukan comic that was running at the time. The comic series was serialized in Shogaku Yonensei, a popular children's publication, and also features a prototype of Charmy Bee. (To the right is a picture of the original manga Amy.)

• Issue #25 (July, 1995) of the Archie comic book features a cover story loosely based on Sonic CD.