EmuNations

Multiple Arcade Machine Emulator is a free and open source emulator designed to recreate the hardware of a wide variety of (mostly vintage) computers, video game consoles and calculators. 

The aim of MAME is to be a reference to the inner workings of the emulated machines; the ability to actually play the games is considered "a nice side effect". The source code to MAME serves as this documentation. The emulator now supports over seven thousand unique games and ten thousand actual ROM image sets, though not all of the supported games are playable. It worth mentioning that the sister-project MESS was integrated into MAME.

Unofficial recent MAME 32-bit versions are available here..

SkyEmu is a low level GameBoy, GameBoy Color, Game Boy Advance and DS emulator. Its primary focus is to provide a good user experience through a good mixture of tradeoffs of accuracy, performance, features and usability...

• Highly accurate Game Boy Advanced emulation

• Game Boy and Game Boy Color Emulation

• Experimental Nintendo DS support (only capable of running homebrew currently)

• Cross Platform: Windows, MacOS, Linux, Web App (with touch screen controls for iOS and Android)

• Game Controller and Rumble Support with configureable keybinds

• 4x Save Slots with screenshot preview

• Game fastforward and rewind support (supporting very long rewind times)

• Support for emulating the Real Time Clock

• CPU, MMIO, and Memory Debuggers

• Dark and Light Themes

• Support for loading official BIOSs dumps

WinArcadia is a multi-system emulator for the following machines::

• Emerson Arcadia 2001 console family (Bandai, Emerson, Grandstand, Intervision, Leisure-Vision, Leonardo, MPT-03, Ormatu, Palladium, Poppy, Robdajet, Tele-Fever, Tempest, Tryom, Tunix...) (1982)

• Interton VC 4000 console family (Acetronic, Fountain, Hanimex, Interton, Prinztronic, Radofin, Rowtron, Voltmace, Waddingtons...) (c. 1978)

• Elektor TV Games Computer (1979)

• PIPBUG- and  BINBUG-based machines (Electronics Australia 77up2 and 78up5, Signetics Adaptable Board Computer, Eurocard 2650...) (c. 1977-1978)

• Signetics Instructor 50 trainer (1978)

• Central Data 2650 computer (1977)

• Astro Wars, Galaxia, Laser Battle and Lazarian coin-ops by Zaccaria (1979-1981)

• Malzak 1 and 2 coin-ops by Kitronix (c. 1980) 

• Chaos 2 computer (1983)

• Dolphin trainer (1977)

• PHUNSY computer (c. 1980) 

• AY-3-8550/8600-based Pong systems (Coleco Telstar Galaxy, Sheen TVG-201...) (c. 1976-1977)

• Ravensburger Selbstbaucomputer aka 2650 Minimal Computer trainer (1984) 

• MIKIT 2650 trainer (1978) 

• VTech Type-right machine (1985)

Features include ReAction GUI, load/save snapshots, windowed and full-screen modes, CPU tracing, trainer, drag and drop support, graphics scaling, automatic load/save of configuration/game, keyboard/joystick/ gamepad/paddle/mouse/trackball support, autofire, turbo mode, gameplay recording/playback, PAL/NTSC modes, sprite demultiplexing, help windows, source code, debugger, frame skipping, redefinable keys, save screenshots (4 supported formats), ARexx port, network play, real-time monitor, locale support, game selection sidebar, text-to-speech, printer output, undithering, support for ZIPped games, clipboard support, palette editor, tone retuning, high score management, force feedback, sprite editor, 3D.