This is not meaningless as the message i replied to claimed that developers who write their own game engine do not finish and publish games. That was factually incorrect.
What you are asking for is something completely different and unless humanity had some sort of hivemind to have universal knowledge, we can't really know as people start and abandon projects all the time.
The best we can do is some heavily biased guesses - and mine would be that the abandoned games in engines like Unity, GameMaker, etc where it is trivial to start a new project would be much more than even other engines (let alone custom engines).
What you are asking for is something completely different and unless humanity had some sort of hivemind to have universal knowledge, we can't really know as people start and abandon projects all the time.
The best we can do is some heavily biased guesses - and mine would be that the abandoned games in engines like Unity, GameMaker, etc where it is trivial to start a new project would be much more than even other engines (let alone custom engines).