If we're talking millions:

I'd pay off my dad's house and get him a small modest little place closer to me that he can live in for now. I'd probably also get a new house, nothing insane but something nicer with room to grow. I don't really mind where I live now but I'd probably buy a place with larger property so I can have alpacas and goats. <3

I'd probably invest a portion or two so that I can continue to earn more.

Then I'd probably put a lot of money into developing games and doing the stuff I've always wanted to do, but limited by my knowledge, being a one-person show, and by my funds.

I'd also travel.