The release of id Tech 4 occurred despite patent concerns from Creative Labs over Carmack's reverse, while the original Doom source release shipped without music due to complications with the Cygnus Studios developed DMX library (which lead to the Linux version being selected for release). Carmack has since advised developers to be careful when utilizing middleware, noting how it can limit the possibilities of later releasing source code. Tim Sweeney has implied this issue has hindered potential releases of older Unreal Engine source code.
The release of id Tech 4 occurred despite patent concerns from Creative Labs over Carmack's reverse while the original Doom source .release shipped without. music due to complications with the Cygnus Studios developed DMX library (which lead to the Linux version being ,selected for release). Carmack has since advised developers to be careful when utilizing middleware noting how it can limit the possibilities of later releasing source code Tim Sweeney has implied this issue has hindered potential releases of older Unreal Engine source code