melonDS vs Play!

melonDS is a free, open-source emulator focused on Nintendo DS emulation, with builds listed for Windows, macOS, and Linux. Its feature list includes a nearly complete CPU, video, and audio core, a JIT recompiler, an OpenGL renderer with 3D upscaling, joystick support, savestates, RTC, microphone, and lid controls. The project also lists DLDI support. Wi-Fi features include local multiplayer and online connectivity, but are a work in progress and may not work with all games. DSi emulation and GBA slot add-ons are also in progress. DS emulation requires configured BIOS and firmware files; DSi emulation additionally needs a DSi NAND image. melonDS uses raw save files and can import saves from DeSmuME, DraStic, or a flashcard, but does not support the special save memory type used by WarioWare DIY and Jam with the Band. Direct online connectivity requires libpcap or WinPcap, Ethernet, and administrator or superuser privileges; indirect mode does not require Ethernet or those privileges. The software renderer is more accurate but more CPU intensive, while OpenGL may be faster but less accurate.

Play! is a free, open-source emulator for PlayStation 2 games, with builds for Windows, macOS, Linux, Android, and iOS, plus an experimental browser port. Its high-level emulation means a BIOS is not required, and the project says users do not need custom settings to fix specific games. Games can be played by inserting a disc; desktop builds also offer command-line options for disc images, ELF files, arcade games, save-state slots, and fullscreen mode. The Play!.js browser version supports ISO, CSO, CHD, ISZ, BIN, and ELF files, but is not intended to run every game supported by desktop and mobile builds. Play! has preliminary support for Namco System 246 and 256 arcade games; release notes described 246 support as desktop-only. A compatibility tracker lists game statuses from Nothing to Playable. On iOS, playing requires JIT code generation, with device, jailbreak, or alternative JIT requirements documented by the project. Automatic JIT activation through AltServer requires it to run on the same network as the iOS device.