Hello!

Well this is definitely not my area of expertise, so please take it with a grain of salt :)

But from what I understand by looking around on the net, since John Riccitiello became CEO of Unity in 2014, he (and other board members, but he led a lot) took several bad decisions that damaged the users' trust in the software little by little.

And also, they were spending a lot to continue to improve the engine while not earning as much (basically, most of their revenues at the moment come from ads on mobile, if I understood correctly).

So this is mostly about a series of questionable decisions, that led to this dire and sad situation :/

As for replacements, there's of course the well known Unreal Engine; and I'm currently diving in (and refocusing) on Godot because it's one of the biggest open-source game engine projects around nowadays, and I think it really has a lot of cool features ;)

Hope it answers your question,c

cheers!