Quake 1.5 is a darkplaces addon mod for the original Quake. Utilizing Seven's SMC 5.30 as a base, it has been expanded to include new features such as weapons, gore, and plenty of level additions.
Quake 1.5 source code, mapping FGD for trenchbroom and map sources
This is another patch with various tweaks and optimizations PATCHES REQUIRE THE INITIAL RELEASE
Here it is, the first SP beta release for Quake 1.5