Editing Sonic CD (section)

== Gameplay ==
[[File:SonicCDTimeTravel.png|thumb|left|alt=A collage of Sonic in the four time periods in the Palmtree Panic level. Clockwise from left: past, present, good future, and bad future.|(''Clockwise from top left'') The past, present, good future, and bad future variants of the Palmtree Panic level]]
''Sonic CD'' is a [[side-scrolling]] [[platform game]] similar to the original ''[[Sonic the Hedgehog (1991 video game)|Sonic the Hedgehog]]''. Players control [[Sonic the Hedgehog (character)|Sonic the Hedgehog]] as he ventures to stop his nemesis [[Doctor Robotnik]] from obtaining the magical Time Stones and conquering Little Planet.<ref name="egrev" /> Like previous games, Sonic can destroy enemies and objects (such as certain walls and television monitors containing [[power-up]]s<ref name="egrev" />) by rolling into a ball, and collects [[Rings (Sonic the Hedgehog)|rings]] as a form of health. Sonic can also perform a "spin dash" and a "super peel-out", both of which increase his speed.<ref name="cvg">{{cite magazine |last=Rand |first=Paul |date=November 1993 |title=Review: Sonic CD |url=https://retrocdn.net/images/d/d0/CVG_UK_144.pdf#page=87 |magazine=[[Computer and Video Games]] |issue=144 |page=87 |access-date=August 29, 2017}}</ref> The game has seven [[Level (video gaming)|levels]]; each is split into three zones, the third of which ends in a [[boss fight]] against Robotnik. Players start with three [[Life (gaming)|lives]], which are lost when they suffer any type of damage without rings in their possession; losing all lives results in a [[game over]].<ref name="segamag" /><ref name="manual" />

''Sonic CD'' is differentiated from other ''Sonic'' games through its [[time travel]] [[game mechanic]], which allows players to access different versions of rounds set in the past, present, and future. The music changes within the different time zones, as remixes of the present music.<ref name="segapro" /> Sonic starts the first two zones in the present. The third zone is always set in the future, its timeline dependent upon whether the player destroyed both transporters in the past.<ref name="egrev" /> He travels through time by hitting signs labelled "past" or "future", maintaining his speed afterward.<ref name="gspotrev" /> By default, future stages are neglected and littered with machinery after Robotnik has conquered the Little Planet, appropriately named "bad futures."<ref name="gspotrev" /> Players are encouraged to convert each zone into a "good future", with bright colors, thriving nature, and few enemies.<ref name="gspotrev" /> To achieve a good future in each zone, players must travel to the past and destroy a hidden transporter where enemy robots spawn. Achieving a good future in every zone unlocks the best ending.<ref name="cvg" /><ref name="gspotrev" />

By finishing a level with more than 50 rings, Sonic can access a special stage, in which he must destroy six [[UFO]]s in a pseudo-3D environment within a time limit.<ref name="egrev" /><ref name="segapro" /> Time is reduced swiftly if the player runs through water, though a special UFO that appears when time is running out grants extra time if destroyed. If the player destroys all the UFOs before the time runs out, they earn a Time Stone.<ref name="manual" /> Collecting all seven Time Stones automatically creates a good future in every zone, unlocking the best ending.<ref name="cvg" /> The game also features a time attack mode, where players can replay completed levels for the fastest time possible; a "D.A. Garden", where players can listen to the music of completed zones; and a "Visual Mode", where players can view the opening and closing animations.<ref>{{Cite web|url=https://www.gamerevolution.com/guides/53880-sonic-cd-ps3-cheats|title=Sonic CD PS3 Cheats|date=January 5, 2012|website=[[Game Revolution]]|url-status=live|archive-url=https://web.archive.org/web/20190405221323/https://www.gamerevolution.com/guides/53880-sonic-cd-ps3-cheats|archive-date=April 5, 2019|access-date=February 10, 2018}}</ref> The game also includes a save feature, which uses the back-up memory of the Sega CD.<ref name="manual">{{cite book|author1=Sonic Team|title=Sonic the Hedgehog CD instruction manual|date=November 1993|publisher=Sega}}</ref>{{rp|20}}