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SCHG How-to

Alter the Ring Requirements in the Special Stages

From Sonic Retro

(Original guide by Mercury)

NOTE: Thanks to MarkeyJester for pointing out to me how to do this.

When Sonic & Knuckles is locked on to Sonic 2, the amount of rings needed to obtain the Chaos Emerald in the Special Stages is reduced. This simple guide will explain how to do the same thing in Sonic 2 alone.

(This guide refers to the Xenowhirl 2007 disassembly)

You'll find the array of ring requirements for a Sonic and Tails game at Misc_7756:

Misc_7756:
	dc.b  30, 70,130,120	; 4
	dc.b  50,100,140,150	; 8
	dc.b  50,100,150,170	; 12
	dc.b  40,100,140,160	; 16
	dc.b  40, 80,150,200	; 20
	dc.b  70,130,200,220	; 24
	dc.b  90,140,180,210	; 28

and the array of ring requirements for a Sonic or Tails game at Misc_7772:

Misc_7772:
	dc.b  30, 70,130,120	; 4
	dc.b  50,100,140,150	; 8
	dc.b  50,100,150,170	; 12
	dc.b  40,100,140,160	; 16
	dc.b  40, 80,150,200	; 20
	dc.b  70,130,200,220	; 24
	dc.b  90,140,180,210	; 28

(If you wish to edit these arrays in raw hex instead of using a disassembly, their offsets are $7756 and $7772, respectively)

Each Special Stage uses 4 bytes, with each byte representing the ring requirement for each section of the Special Stage. This means that the fourth byte is unused, because all the special stages are only 3 sections long.

The Special Stages are stored in the array - as you'd expect - in order from the first to the seventh.

SCHG How-To Guide: Sonic the Hedgehog 2 (16-bit)
Fixing Bugs
Fix Demo Playback | Fix a Race Condition with Pattern Load Cues | Fix Super Sonic Bugs | Use Correct Height When Roll Jumping | Fix Jump Height Bug When Exiting Water | Fix Spin Dash Code and Add Spin Dash Speeds | Fix Screen Boundary Spin Dash Bug | Correct Drowning Bugs | Fix Camera Y Position for Tails | Fix Tails Subanimation Error | Fix Tails' Respawn Speeds | Fix Accidental Deletion of Scattered Rings | Fix Ring Timers | Fix Rexon Crash | Fix Monitor Collision Bug | Fix EHZ Deformation Bug | Correct CPZ Boss Attack Behavior | Fix Bug in ARZ Boss Arrow's Platform Behavior | Fix ARZ Boss Walking on Air Glitch | Fix ARZ Boss Sprite Behavior | Fix Multiple CNZ Boss Bugs | Fix HTZ Background Scrolling Mountains | Fix OOZ Launcher Speed Up Glitch | Fix DEZ Giant Mech Collision Glitch | Fix Boss Deconstruction Behavior | Fix Speed Bugs
Design Choices
Remove the Air Speed Cap | Disable Floor Collision While Dying | Modify Super Sonic Transformation Methods & Behavior | Enable/Disable Tails in Certain Levels | Collide with Water After Being Hurt | Retain Rings When Returning at a Star Post | Improve the Fade In\Fade Out Progression Routines | Fix Scattered Rings' Underwater Physics | Insert LZ Water Ripple Effect | Restore Lost CPZ Boss Feature | Prevent SCZ Tornado Spin Dash Death | Improve ObjectMove Subroutines | Port S3K Rings Manager | Port S3K Object Manager | Port S3K Priority Manager | Edit Level Order with ASM‎ | Alter Ring Requirements in Special Stages | Make Special Stage Characters Use Normal DPLCs | Speed Up Ring Loss Process | Add beta spindash to Sonic 2 | Change spike behaviour in Sonic 2
Adding Features
Create Insta-kill and High Jump Monitors | Create Clone and Special Stage Monitors | Port Knuckles
Sound Features
Port Sonic 1 Sound Driver | Port Sonic 2 Clone Driver | Port Sonic 3 Sound Driver | Expand the Music Index to Start at $00 (Sonic 2 Clone Driver Version)
Extending the Game
Extend the Level Index Past $10 | Extend the Level Select | Extend Water Tables | Add Extra Characters | Free Up 2 Universal SSTs