i suggest games-engines from the page: "The indiana library aims to help developers of classic (2d) adventures to do their job (thinking about story, puzzles and art). It is implemented in the wonderful D Programming Language using SDL and some of its extensions (for example SDL_ttf)" there is also an editor there for it (atlantis on the same page). dev-util/dsss is needed as buildsystem https://bugs.gentoo.org/show_bug.cgi?id=218244
Created attachment 153445 [details] ebuild
can be bumped to 0.0.3, no problems