Complex sentence: It runs on mainly on Windows, Linux, OpenBSD and Mac OS X systems using OpenGL and SDL, although an unofficial FreeBSD port is available and a primitive Dreamcast port exists, as well as a version for the Wii.
Split into simpler sentences: It runs on mainly on Windows, Linux, OpenBSD and Mac OS X systems using OpenGL and SDL. An unofficial FreeBSD port is available and a primitive Dreamcast port exists, as well as a version for the Wii.