Hobby during PhD studies has taken its toll, how do I recover?
There's an obvious simple answer to this, that isn't going to even take two sentences:  your game development stint was research.  Research into whether gaming concepts and/or game-style interfaces were useful for certain kinds of activities, and also a "basic training" for you in core computing concepts that will never be irrelevant in your ongoing pursuit.

Professional coders have MOUNTAINS of code that are discarded, serve no useful ongoing purpose, are total feces, and/or seem to be in a content domain that bears no relevance to their work.

Myself personally:  I have about 10k lines of code growing mold in a drawer somewhere for a dartboard app. It isn't worth spit, but the javascript I write NOW for the biggest banks in the world is quite better because of it.

You also discovered that you like your profession more than you like gaming.  That's NOT AT ALL a trivial result.