Hi, the Doom source port called "ZDoom" is released under two licenses that aren't present in /usr/portage/licenses: the "DOOM" and the "BUILD" license. I'll open this bug report to make it a dependency for Zdoom ebuild bug report.
Created attachment 162808 [details] "BUILD" license "BUILD" license
Created attachment 162809 [details] "DOOM" license
We don't need this now that we have gzdoom.