Game Boy Color Core:

Game Boy Color emulation added — full CGB support in the SGB core.
CGB-mode rendering, palette/color handling, and automatic CGB loading for CGB carts.
Fixes CGB rendering under the SGB BIOS and refines cart routing so GB/GBC/SGB titles dispatch correctly.

Game Boy:

New PPU debugger viewers — GB tile viewer, tilemap viewer, and sprite/OAM viewer, plus per-layer toggles.
S-PPU and GB-PPU viewer menus are now context-enabled based on the loaded roms.
MBC1 multicart (MBC1M) support — BANK2<<4 game-slot select so multicarts like "Mortal Kombat & Mortal Kombat II" boot to the correct game bank.
APU DAC DC-bias modeling — models the DAC's DC bias so master-volume-driven PCM voices (NR50 PCM + CH4 carrier) are no longer cut off.
Fixes half-playing digitized voices (e.g. Bart Simpson voice samples).
Square-channel duty reset on trigger (master c0d9941) — resets square duty position on channel trigger, fixing the silent/garbled Telefang title-screen PCM voice jingle.
Toggle Sprites/Background/Window layers.

Controller image switcher — USA / Euro-Japanese controller image selector in the Input Config dialog using right click on the image.
Input config multi-bind fixes — fixes multi-bind / single-bind glitches in the input configuration dialog.