fixNES vs HalfNES

fixNES is a free, open-source NES emulator for Windows and Linux. It runs NTSC and PAL .nes ROMs and creates .sav files for games that support saving. FDS and QD titles can run when a FDS BIOS named disksys.rom is placed in the same folder, and NSF music files are supported with track changes on the left and right keys. Files can be opened by drag and drop, command-line argument or from ZIP archives. The project lists support for NES mappers and VRC6, VRC7, FDS, MMC5, N163 and Sunsoft 5B audio expansions. Controls are keyboard-only; Windows users can use joy2key for controller input. The standalone build uses supplied scripts and requires freeglut and openal-soft, while a Makefile supports RetroArch core use. The README says the project is not in its most complete or cleanest state. It is licensed under MIT.

HalfNES is a free NES and Famicom emulator for Linux, macOS, Windows, and other Java-compatible platforms. It supports the mapper numbers listed in its README, and says nearly all US releases will start, though some can show corrupted graphics or freeze. Its audio features include a sound core and an NSF player; display options include full screen and an NTSC filter. Controls can be remapped in Preferences, and joysticks work through DirectInput and xInput. HalfNES supports battery saves, but not savestates. GitHub releases provide a Windows executable and a JAR for other platforms, and both require Java 8 or newer. Linux users need to set execute permission on the JAR. Gamepads must be connected before a game loads to be detected, and their buttons cannot be configured. PAL games are supported but may have more issues; users need to select PAL in Preferences. The README gives a 2 GHz Athlon 64 or better as the requirement for full-speed play across all games, and notes that the NTSC filter needs substantially more processing power.