Spearmint is another open-source game engine project. The objective of Spearmint is to build upon the ioquake3
game engine with further improvements. While it adds in some features, Spearmint has yet to see any widespread adoption.
Spearmint is a GitHub project
that self-describes itself as "a version of ioquake3 which may be used for further development of standalone games."
Features implemented for Spearmint include four-player split-screen support, better virtual machine (QVM/DLL/SO.DYLIB) API handling, improved virtual machine system calls with unified shared calls, a modified pure PK3 system, removed code not needed for standalone games like CD key handling and the PunkBuster UI, Ogg Vorbis support by default, and FreeType support by default.
This work is on top of existing ioquake3 features like its SDL back-end, OpenAL audio, x86_64 Linux support, MinGW support, VoIP, improved QVM tools, HTTP/FTP download redirection, PNG support, and much more.
While Spearmint hasn't found its way in use by any major open-source game project yet, the engine is actively developed and the most recent Git activity is from last week.