This film has many layers to it and since I love visual clues in movies, I enjoyed the recurring themes of Justice the mythical fish, the black cat, Plymouth Island, etc. But the best part of the movie for me was this - and spoiler alert - while the movie doesn't make this completely clear, it IS how I interpret it.
Spoiler Alert ahead! You were warned!
Yes, the dad is an artificial intelligence created by the genius son. But he is more than that. He is also the dad's soul and has been enrolled into the game his son has created, precisely because he has not made peace with his own death and he misses his son.
The true genius of the computer game this young man designed is that it crosses over into other realms of reality.