::====================
::Retro COVID Captives
::By eskayelle
::May 2020
::====================
::
::**CONTENTS**
::
::*****INTRODUCTION*****
::*****VERSION HISTORY*****
::*****TOOLS USED*****
::*****CREDITS*****
::
::
::*****INTRODUCTION*****
::
::A graphics hack based on Taito's Space Invaders for the Gameboy (and Super Gameboy!), 
::Retro COVID Captives grabs those lovable Dr. Mario virus sprites
::and puts them in an unprecedented situation.
::
::With the apartment buildings next door taking most of the hits, 
::yours is the last house on the block (and perhaps in the city) 
::that hasn't been infected with the coronavirus.  
::
::Armed with an experimental vaccine, motor(home) your way through 
::as many strains as you can before COVID-19 takes over your household.  
::All the while, fight back against misinformation and pseudo-cures.  
::
::How many rounds will your stay-at-home strategy last?
::
::Fight the good fight!
::Stay home!
::Stay safe!
::Play this game!
::
::This hack is a follow-up to my previous COVID Captives hack for the Famicom/NES,
::given how much I enjoyed practicing sprite replacements, text tables, and debugging.
::
::The Retro COVID Captives vx.x [U] [h].gb file is a modified original Gameboy Space Invaders ROM.
::The romhack is distributed as an IPS patch, which should be patched to an original Space Invaders ROM. 
::
::The ROM can be opened and played via several emulators, including in Windows, 
::Linux, and Android environments.
::
::
::*****VERSION HISTORY*****
::
::v1.0 (May 2020):
::Located the tiles for the SGB Space Invaders borders and removed them via TileMolester.
::Using BGB's debugger and xvi32 for hex editing, 
::located the code for pressing to move from SGB to arade mode and NOP'd that ability.
::This cuts access to the SNES Space Invaders game and focuses on the Gameboy one.
::Removed the tiles for the SGB and arcade icons on the first SGB screen via TileMolester.
::NOP'd the call for the sound that plays when pressing left/right on the first SGB screen.
::Coded 3E 08 00 to $2FDF to force the game to register the Start button as pressed,
::which effectively passes the first SGB screen immediately.
::Coded 00 00 00 to $2FE8 to remove the call to the sound played when Start is pressed on the first SGB screen.
::Using TileMolester, located and removed all text tiles on the first SGB screen.
::Made various ASCII text edits via xvi32.
::Using BGB's VRAM reviewer and xvi32, located the tiles for in-game text;
::changed their values to reflect the COVID Captives Double Z mod.
::(Tables are near $2A3F in ROM.)
::Using BGB, changed the * tile to a :.
::Using BGB, changed certain sprites to reflect those used in my Famicom COVID Captives hack 
::(sprites based on NES Dr. Mario).
::Using Tile Layer Pro, imported a title screen bitmap for Retro COVID Captives into a "scratch" ROM.  
::Used that ROM to align the tile for the original title screen (18 x 8 overall, 
::but actually a 12 x 4 and an 18 x 4 set) and then moved the individual tiles over to the hack.
::Located the tiles for the shields at $2B55 and converted them to apartment buildings using TileMolester.
::Fixed header and ROM checksums using BGB.
::
::
::*****TOOLS USED*****
::
::TileMolester v0.16
::Tile Layer Pro v1.1
::xvi32 v2.55
::BGB v1.5.7
::
::
::*****CREDITS*****
::
::eskayelle for all ASM hacking and sprite and tile edits within this hack.
::Taito for the original Gameboy / Super Gameboy game.
::Nintendo for them Dr. Mario sprites.
::John Riggs for his YouTube channel on hacking NES games.
