Versatile Commodore Emulator
VICE is an emulator collection which emulates the C64, the C64-DTV, the C128, the VIC20, practically all PET models, the PLUS4 and the CBM-II (aka C610). It runs on Unix, MS-DOS, Win32, OS/2, Acorn RISC OS, BeOS, QNX 6.x, Amiga, GP2X or Mac OS X machines.
Open-source, free, multi-platform BASIC compiler, with syntax similar MS-QuickBASIC (including the GFX statements), that adds new features such as pointers, unsigned data types, inline assembly, a pre-processor and many others.
Emulator of Atari 800/800XL/130XE/5200 with various extensions (1088kB RAM, stereo sound and much more) running on just about every operating system (Unix/Linux, Windows, DOS, TOS, MacOS, Workbench, WinCE...)
Hammer of Thyrion (uHexen2) is a cross-platform port of Raven Software's Hexen II source. It is based on an older linux port, Anvil of Thyrion. HoT includes countless bug fixes, improved music, sound and video modes, opengl improvements, support for many operating systems and architectures, and documentation among many others.
FakeNES is a highly portable, Open Source NES and Famicom emulator. It runs on all modern operating systems and has an actively maintained DOS port for enthusiasts. Support for phones and other mobile platforms is under development. The majority of the project is entirely original code released under the zlib/libpng license. Contributed and third-party code is included under GNU licenses.
Jainja is a JVM (Java Virtual Machine) written in Java
Drum machine compiler, generic music sequencer and mixer: Write or generate drum and tone patterns in a simple programming language. Mix it using the sample assembler (asampler). Renders to files or plays real-time. Very portable. Works on old hardware.
a free, multiplatform console-mode gopher client
Gopherus is a free, multiplatform, console-mode gopher client available for DOS, Linux and Windows. It provides a classic text interface to the gopherspace. Altough primarily targeted for DOS, ports to Windows and Linux are also available. These use SDL2 to emulate a pseudo terminal.
Android, DOS, FirefoxOS, Linux, MacOS and Windows all in one..
Sensa is not an operating system, is a work environment compatible with Android © 4.4.4, Firefox OS ©, Linux Ubuntu 12.12 ©, MacOS Classic 7 ©, MS -DOS © operating systems, and Microsoft Windows 8.1 ©; whose distribution is free, and with source code available under GNU GPL 2.0 license .
A quick-and-dirty maze game written in pure text-mode C with an available SDL frontend. Find the goal and make it to the exit.
MegaZeux (MZX) is a simple but powerful game creation system. It currently officially builds on Windows (9x, 2k, XP), Linux (multiplatform), and MacOS X. Versions prior to 2.80 are available only for MS-DOS.
A 2D top-down fast paced racing game, originally written for DJGPP, now it targets SDL and net-play. Inspiration to write it came from playing some Australian 3D racing game with "slide" in its name.
Tools and file format documentation for Microprose F-15 Strike Eagle III