Source ports share the similarity with unofficial patches that both don't change the original gameplay as such projects are by definition mods.
While the primary goal of any source port is compatibility with newer hardware, many projects support other enhancements.
Common examples of additions include support for higher video resolutions and different aspect ratios, hardware accelerated renderers (OpenGL and/or Direct3D), enhanced input support (including the ability to map controls onto additional input devices), 3D character models (in case of 2.5D games), higher resolution textures, support to replace MIDI with digital audio (MP3, Ogg Vorbis, etc.
To address this shortcoming, specific source ports such as Skulltag added "lobbies", which are basically integrated chat rooms in which players can meet and post the location of games they are hosting or may wish to join.
If the source code of a software is not available, alternative approaches to achieve portability are Emulation, Engine remakes, and Static recompilation.