jgb (Source)
jgb is a cross-platform low-level Game Boy [Color] emulator with no game-specific logic or game-specific hacks. It is not completely cycle-accurate due to CPU emulation being instruction-based rather than cycle-based, but it should be able to run the vast majority of licensed Game Boy and Game Boy Color games.
* Game Boy and Game Boy Color emulation
* Support for cartridges using MBC1, MBC2, MBC3, MBC5, MBC7 mappers
* Save file / cartridge RAM persistence to disk
* Keyboard input and DirectInput gamepad support
* Support for the MBC3 real-time clock with persistence to disk
* Support for MBC5 rumble cartridges (requires a gamepad with rumble)
* Support for the MBC7 accelerometer (requires a gamepad with an accelerometer)
* 2x fast-forward toggle
* Save & load state
* Three different color palette options for GB mode (black & white, light green tint, intense lime green)
* Option for GBC color correction to more closely mimic how games looked on the Game Boy Color LCD
* Option for integer scaling regardless of window/display size