By the Mania, for an Encore, with an Addendum!

Overview:

Welcome to Sonic Mania Addendum, an extensive full-game edit + expansion for Sonic Mania Plus!

Addendum adds a few completely new features to Mania, such as:

• Extra Slot Amy - Adds Amy Rose as her own character, meaning there are now 6 playable characters! She remains mostly the same from the previous iteration of the standalone mod, with additional control updates, such as using the right bumper to Hammer Jump, to make the move easier to use for controller players.
• Time Stones - Adds the Time Stones from Sonic CD as a separate set of collectables, allowing one to complete 14 Special Stages in a single playthrough to get both sets of gemstones. Collecting all Time Stones gives a few passive benefits, such as extending the duration of invincibility and speed shoes, weakening (most) bosses, and...
• Miracle Forms - Collecting all Time Stones allows the player to enhance their Super form into a Miracle form, giving benefits such as a further increase to speed and jump height and a new sprite set for each character.

Addendum primarily focuses on overhauling some integral game concepts, such as cooperative multiplayer, player physics, and shield interactions, and adding an abundance of quality-of-life features to the game. Some of the most notable changes are:

• Act Select - Overhauls Data Select to allow save files to save the current act, removing the annoyance of having to restart an entire zone if leaving the game during Act 2. Completed save files can select between acts by pressing Z (keyboard) or Select (controller)
• Co-op Plus - Overhauls Mania Mode multiplayer by enhancing the P2 experience, such as giving both P1 and P2 a power-up when breaking an item monitor, allowing P2 to break item monitors (only if controlled by a player; AI P2 cannot break item monitors), and having P2 transform into a Super/Miracle form alongside P1.
• Unrestricted Unlocks - Removes the medallion requirement for all Secrets menu unlocks, allowing even the newest of save files to access every Secrets menu unlock.
• Power-up Display - Adds a new HUD element that keeps track of P1's current power-ups, as well as flashing indicators if a Super/Miracle form, invincibility, or speed shoes are about to run out.
• Flight Re-curl - Allows Tails to cancel his flight by pressing Down + Jump.
• Player Palette Overhauls - Overhauls almost all player palettes, mainly to fix some questionable underwater palette choices (for example, Tails and Knuckles' Super CPZ palettes), and to make all underwater player palettes realistically comparible to one another.
• Player Sprite Tweaks - Adds extensive edits to all character sprites to fix some vanilla palette issues with Super forms (most notably being Tails' shoes, Knuckles' skin, and Mighty's skin/legs)
• Shield Saving - Allows for players to keep their shields between zones, instead of only purely between acts.
• Super Run (Competition) - Adds a new game rule to Competition Mode, allowing players to start out the stage in their Super or Miracle form, with 55 rings to compensate for the Announcer countdown.
• 1-up Music Removal - Removes the 1-up music from playing when obtaining an extra life, instead opting for a shorter sound effect to not disrupt the level music or invincibility/speed shoes music.
• Knuckles Moveset Improvements - Modifies Knuckles' moveset to allow him to spindash immediately out of a glide drop/slide by holding down, as well as allowing Knuckles to re-curl into a spinball by pressing Down + Jump during a glide drop.
• Air Curl - Allows all players to press Down + Jump while in the air and not in a spinball to curl back into a jump state, to better avoid situations to where the player would fall onto an enemy and lose their shield/rings.

Lastly, Addendum fixes a few vanilla game bugs/oversights, such as:

• "Instant Mach" Bind Removal - Removes the ability for the player to instantly gain a Mach level by pressing the Y key in Special Stages.
• Peelout Transfer Removal - Fixes an oversight in the character swapping code that previously allowed other characters to use the Super Peel-out by enabling the Peel-out medallion mod and breaking a character swap monitor as Sonic.
• LRZ3 Encore Master Emerald Fix - Fixes an oversight with the Encore palette system that would make the Master Emerald purple in Encore Mode.
• Cutscene Death Egg Robot Chasis Fix - Implements a code fix for the Death Egg Robot's underside being orange instead of black in the GHZ2 Outro cutscene.
• Mighty MBM Sprite Fix - Completely re-sprites Mighty's Puyo-Puyo animations to actually use his palette, as well as not being an MBM Sonic redraw.
• Super Form Black Palette Fix - Modifies each character's "blend Super palette" function to fix an issue where the color adjacent to a character's palette would turn black, leading to issues such as the infamous Mighty black skin bug.
• Spindash Moonwalk Fix - Adds a spindash state check to prevent an issue to where spindashing while touching the left side of a solid object and holding left would result in the player moving backwards while in the spindash state.
• MBM Sprite Mirroring Fix - Implements a code fix for a small visual bug to where after the MBM character intro animation was played, the character would go from looking up and right to immediately looking up and left.
• Heavy King LRZ3 Hitbox Fix - Tweaks the Heavy King's hitbox values to fix a bug to where Heavy King's hurtbox was upside-down and only 4 pixels tall.
• "Mach Up" Power-up Overhaul - Tweaks the functionality of the "Mach Up" power-up in Special Stages to give one entire Mach quota rather than just manually setting the Mach speed to the next level and resetting the sphere count. This circumvents the issue of Mach Ups becoming less effective the higher the Mach meter is.

All game changes can be found in the changelog.txt file, and player controls can be found in the controls.txt file, both in the attached download below.

This mod is still a heavy WIP, so expect bugs and crashes! I will be making Addendum's Github repository public after the SHC Contest week ends, so if you can replicate an issue more than once, please submit an Issue to the Github repo!

Setup:

THIS MOD REQUIRES THE SONIC MANIA DECOMPILATION TO USE!

THIS MOD REQUIRES THE ENCORE DLC TO USE!

THIS MOD REQUIRES THE LANGUAGE TO BE SET TO ENGLISH TO USE!

DO NOT USE OTHER MODS ALONGSIDE ADDENDUM!

Sonic Mania Addendum functions differently than other Mania mods, and doesn't make use of GameAPI. Rather, Addendum is a source code edit to Mania, meaning that in order to properly use this mod, one needs to enable the mod's assets with the mod loader and also replace the vanilla Mania Game.dll file with a custom-made Game.dll for Addendum, four versions of which are attached below, two for RSDKv5 (x64 and x86) and two for RSDKv5U (x64 and x86). The attached .zip file should be able to be directly extracted into the root directory of a Mania decomp folder, given that it's set up correctly. After choosing the correct DLL for your RSDKv5 version, you NEED to rename it to just Game.dll for RSDKv5 to load Addendum's code.

Addendum also uses custom save data, using SaveDataAddendum.bin for saving vanilla save data, and AddendumOptions.bin for Addendum-specific save data, notably being Time Stone progress. It is possible to transfer vanilla save data by renaming a SaveData.bin file to SaveDataAddendum.bin, although I cannot guarantee 100% save file compatibility by doing this.

Known Bugs:

• The cutscenes between GHZ2 --> CPZ1 and PGZ2 --> SSZ1 are known to crash when carrying over a shield between these zones in single player. Skipping these cutscenes or having a Player 2 prevents this crash.
• A rare bug may occur when loading into the Main Menu to where the game will not properly load main game and Addendum save data. Going back to the Title Screen and re-entering the Main Menu, or pressing F5 with the dev menu enabled should re-load the save data.