Is the use of the word "godly" to describe something in a video game—without intending its literal meaning, and with the user being ignorant of the religious ruling at the time, followed by an attempt to change it later—considered an apostasy or does it necessitate sin and punishment?

You have not committed shirk (polytheism), and what you are experiencing is obsessive-compulsive disorder caused by giving in to the whispers and not striving against them. The best cure for these whispers, after seeking Allah's help, is to ignore them and pay no attention to any of them.

What you asked about are mere satanic whispers that have no reality, and you are upon Islam. The beneficial cure for repelling these whispers is to turn to the remembrance of Allah and do so frequently, and to feel joy when experiencing them, because that displeases Satan. Ibn Hajar al-Haytami mentioned that the effective remedy for obsessive whispers is to completely ignore them, for whoever gives ear to them will find them increasing until they drive him to the realm of the insane. Al-Izz ibn Abd al-Salam and others believe that obsessive whispers are satanic thoughts, and fighting them is considered a form of jihad.