Cross-compatibility was planned for the Xbox Live Arcade and Windows Phone versions, allowing players to alternate their games by means of Cloud saving, but the idea was removed because the Windows Phone version was cancelled.
Owners of both Episode I and II on the same system can unlock free "Episode Metal" content in Episode II. "Episode Metal" explains how Metal Sonic came back to life after being defeated in Sonic CD, and players can play as Metal Sonic through four acts, all of which are reworked from the first act of each Zone in Episode I.
Plot
Metal Sonic survived his previous defeat in Sonic CD, but was severely damaged, and left on Little Planet when it disappeared at the end of the game. After the events of Episode I, Little Planet returns, and Dr. Eggman locates and repairs Metal Sonic. Sonic hears that Eggman is back, and reunites with Tails to stop him. Meanwhile, Metal Sonic, after receiving a mysterious power source, searches for the heroes and sees them fly away in the Tornado, following them using Tails' rocket.
It is revealed that Eggman plans to construct a new Death Egg mk.II over Little Planet. As the dwarf planet heads back into space, Sonic and Tails follow the villains to the Death Egg. Inside, they confront and defeat Metal Sonic. Later, they defeat Eggman at the heart of the base. Sonic and Tails then escape via space pods just before the Death Egg begins to explode. As the credits roll, the duo head back to Earth while the Death Egg shuts down.
Development
In February 2011, Sonic the Hedgehog 4: Episode II was confirmed to be in early development. Sega Brand Manager Ken Balough stated that "the idea is to introduce new zones with things you haven't seen." He has also hinted that Episode II may have a larger budget than Episode I, due to the commercial success of Episode I. Balough also stated that many of the ideas in Episode II were planned while the first episode was still under development. Sega of America Community Manager Aaron Webber also hinted that Tails may appear in Episode II. On August 23, 2011, Sonic Team head Takashi Iizuka stated that "this year, 2011, is the anniversary, so we're focusing on the celebration title, but moving forward to 2012, Sonic will still be going, so I'd hope to provide Episode 2 then." He also said that Sonic Team "knew about the anniversary year," and that "Generations was planned way in advance." As such, "it was always our plan to release Episode 2 after Generations." In preparation for Episode II's release, Sega re-released Sonic the Hedgehog CD to digital platforms in late 2011, billing it as a 'prequel' to Sonic 4, as the events of Episode II would rely heavily on what occurred in CD.
On December 29, a teaser trailer for Episode II was released, and it was revealed that both Metal Sonic and Tails would be returning. It was also revealed that the game would feature an updated graphics and physics engine from Episode I. Platforms confirmed for release were Xbox Live Arcade, PlayStation Network, iOS, Android, Windows Phone and PC. It was also confirmed that no WiiWare version of Episode II would be released, with it being highly assumed that the Wii version was cancelled due to hardware constraints.
On April 21, 2012, an early beta version of Episode II was accidentally made available to people who pre-ordered the game on Steam. However, Sega quickly removed it.
In March 2012, Iizuka has said that Sega was not planning on releasing any further episodes of Sonic 4. In 2015, it was revealed that Sonic 4 was originally conceptualized as a trilogy, but it was considered a duology because plans to develop Episode III were abandoned for undisclosed reasons.
Reception
Sonic the Hedgehog 4: Episode II received mixed reviews. Review aggregator website Metacritic gave the PlayStation 3 version 63/100, the Xbox 360 version 61/100, the PC version 54/100, and the iOS version 66/100.
IGN's Lucas M. Thomas gave the game a score of 6.5, stating that while it fixes the physics problems of Episode I, it is still missing the "magic" of its Genesis predecessors. GamesRadar+'s Lucas Sullivan criticized it in similar ways, stating that the two-player mode "seems to prioritize griefing your friends instead making real in-game progress," and further stating that "every time we felt like we were reliving our old Sonic glory days, the next stage would incorporate limp and uninspired gimmicks like shifting winds or avalanche snowboarding." Electronic Gaming Monthly's Ray Carsillo gave the game a 6.5, praising the "old-school Sonic" aspects of the gameplay, but criticizing the Tails-related gameplay, stating "there were too many puzzles that required Tails' assistance." Joystiq's Richard Mitchell had mixed feelings on the game as well, awarding it 3 out of 5 stars, and stating "Episode 2 makes improvements over its predecessor, with better visuals, useful co-op maneuvers and great special stages, but the inconsistent boss battles and uninspired level design keep it from recapturing Sonic's glory days." GameTrailers gave the game a score of 5.5, saying that the level design and the team-up moves often slow the pace of the game. Official Xbox Magazine's (UK) Jon Blyth was more positive, concluding that the game was "a smooth, slippery Sonic that takes another step away from it's sic single-button origins without losing any of the hog essence. With local and online co-op, it offers just enough entertainment to justify its steep episodic price."