Sonic the Hedgehog (2013)

The 2013 re-release of Sonic the Hedgehog is a remastered downloadable remake of the original Sonic the Hedgehog for the Sega Mega Driveon the iOS and Android mobile platforms. It was released on 15 May 2013 for iOS and on 16 May 2013 for Android. The iOS is also a free update to those who purchased the earlier iOS port of the game. It was developed by Christian Whitehead and Headcannon using the Retro Engine, the same game engine used for the 2011 re-release of Sonic the Hedgehog CD.

Gameplay
The gameplay remains generally faithful to the original Sonic the Hedgehog but it runs at 60 FPS, has widescreen support and a remastered soundtrack. In addition, the game has received new features and gameplay changes.

New features

 * The Spin Dash is now included as an optional move.
 * Despite not being officially introduced yet in the series, Miles "Tails" Prower and Knuckles the Echidna are unlockable characters, with mild tweaks to the level design to accommodate their gameplay. They both retain the same movesets they had in Sonic the Hedgehog 3 & Knuckles. Tails can also accompany Sonic like he did in Sonic the Hedgehog 2 and Sonic the Hedgehog 3 & Knuckles.
 * Tails is unlocked by completing the game once while Knuckles is completed by completing the game with all six Chaos Emeralds.
 * A hidden seventh Chaos Emerald and Special Stage was included via Level Select.
 * As such, super transformations of Sonic, Tails and Knuckles are also enabled.
 * Another "custom" Special Stage is accessible via Level Select where it can be designed and edited by the player using Debug Mode. Once saved, it will then become the current seventh Special Stage that will override the default seventh Special Stage.
 * A Time Attack mode is included.
 * The hidden Level Select and Debug Mode options are greatly expanded, taking elements from the sequels as well as incorporating recreations of unused content.

Changes

 * The life count is now displayed at the top-right corner of the screen as opposed to being located at the bottom-left corner of the screen.
 * The title screen now changes based on the player's characters. As such, it can alternatively display Miles "Tails" Prower in Sonic the Hedgehog (for Tails alone), Sonic the Hedgehog & Tails (for Sonic and Tails) or Knuckles the Echidna in Sonic the Hedgehog (for Knuckles alone).
 * Spikes on the wall and Rings in the air that can only be reached by Tails or Knuckles have been added above the Lamppost between the two S-tunnels near the end of Green Hill Zone Act 1.
 * The boss of Green Hill Zone has a wider arena and also, Dr. Robotnik can no longer be prematurely attacked until the wrecking ball has been fully deployed.
 * At Marble Zone Act 1, climbing or flying to the top of the wall now reveals an Invincibility Monitor. When climbing/flying to the top of the wall at Marble Zone Act 3, a new passage is implemented from there.
 * At Special Stages, the stages now rotate smoothly.

Cheat codes

 * Level Select: Start a game in "NO SAVE MODE". At the opening Sega logo, touch the letters S, E, G, A in that order. When the title screen appears, press the screen with two fingers at once. You will be taken to a new level select screen, very similar to the one from Sonic the Hedgehog 2. One can change their playable character, Spin Dash options, speed cap options, and Spikes options (activating the old lack of invulnerability for spikes or not).
 * All Chaos Emeralds: Go to the Level Select Sound Test and play the following tunes in this order 04, 01, 02, and 06 from the Sound Test.
 * Super Sonic: Perform the level select code then the All Chaos Emeralds code. On the level select change the Max Emeralds setting from 6 to 7. Then you can use Super Sonic after collecting 50 Rings in any stage. You should replay the All Chaos Emeralds code first. This can be used for Super Tails and Super Knuckles. Note: Super Tails won't have Flickies.
 * Play any Special Stage: At the Level Select Sound Test, play a tune between 00-07 inclusive. Then select Special Stage.
 * Debug Mode: From the level select, play sounds 01, 09, 09, 01, 00, 06, 02, and 03 in that order from the Sound Test. After starting a level, tap the GUI in the top-left corner of the screen to activate/deactivate debug mode.
 * Character Select: From the level select, change the player option from 00-03. 0 is Sonic and Tails, 1 is Sonic, 2 is Tails, and 3 is Knuckles.
 * Change Tails' name to Miles - When the Sega logo appears, tap the letters A-G-E-S in that order. This can be done either in starting a new game normally or in No Save Mode. This applies to Tails' life count and the title screen will change to Sonic the Hedgehog & Miles.

Trivia

 * At the Sega logo, if the player taps the letters A-G-E-S, then instead of the "SONIC TEAM PRESENTS" screen, the player is treated to a screen displaying hidden credits in Japanese as seen in the image to the right.
 * The Debug Mode code (01, 09, 09, 01, 06, 02, 03) is a reference to the release date of the original release date of Sonic the Hedgehog (23 June 1991).
 * This port marks the first game since Sonic Advance 3 that Knuckles can be accompanied with Tails.