From Quake Wiki
Very alpha (=incomplete) in game level-editor for the FTEQW engine.
CraFTEr *should* be a realtime game editor, but, right now is not even a working level editor. Too many features missing or not fully working and too little time to dedicate. This is a completely rewrite from the one shown in this video, so, it iss pretty basic for now.
See more release information InsideQC thread