/usr/include/crystalspace-2.0/iengine/ is in libcrystalspace-dev 2.0+dfsg-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/crystalspace-2.0/iengine/camera.h
/usr/include/crystalspace-2.0/iengine/campos.h
/usr/include/crystalspace-2.0/iengine/collection.h
/usr/include/crystalspace-2.0/iengine/collectn.h
/usr/include/crystalspace-2.0/iengine/engine.h
/usr/include/crystalspace-2.0/iengine/halo.h
/usr/include/crystalspace-2.0/iengine/impman.h
/usr/include/crystalspace-2.0/iengine/imposter.h
/usr/include/crystalspace-2.0/iengine/light.h
/usr/include/crystalspace-2.0/iengine/lightmgr.h
/usr/include/crystalspace-2.0/iengine/lod.h
/usr/include/crystalspace-2.0/iengine/material.h
/usr/include/crystalspace-2.0/iengine/mesh.h
/usr/include/crystalspace-2.0/iengine/meshgen.h
/usr/include/crystalspace-2.0/iengine/movable.h
/usr/include/crystalspace-2.0/iengine/objwatch.h
/usr/include/crystalspace-2.0/iengine/portal.h
/usr/include/crystalspace-2.0/iengine/portalcontainer.h
/usr/include/crystalspace-2.0/iengine/renderloop.h
/usr/include/crystalspace-2.0/iengine/rendermanager.h
/usr/include/crystalspace-2.0/iengine/rendersteps/
/usr/include/crystalspace-2.0/iengine/rendersteps/icontainer.h
/usr/include/crystalspace-2.0/iengine/rendersteps/igeneric.h
/usr/include/crystalspace-2.0/iengine/rendersteps/ilightiter.h
/usr/include/crystalspace-2.0/iengine/rendersteps/irenderstep.h
/usr/include/crystalspace-2.0/iengine/rendersteps/irsfact.h
/usr/include/crystalspace-2.0/iengine/rview.h
/usr/include/crystalspace-2.0/iengine/scenenode.h
/usr/include/crystalspace-2.0/iengine/sector.h
/usr/include/crystalspace-2.0/iengine/sharevar.h
/usr/include/crystalspace-2.0/iengine/texture.h
/usr/include/crystalspace-2.0/iengine/viscull.h