He used this open source engine, it is free. He is almost certainly getting between 60-70% of revenue after distribution fees. His only other expenses are taxes and the other devs he employs and he was solo until the game made like $100 million. Most of the copies sold for $15 so it seems fair to me to say his companies lifetime revenue is close to $10*number of units sold which is close to half a billion dollars. And since the companies expenses are effectively zero profit is the same. If he’s smart with taxes he’s paid 15% corporate tax rate then 15% capital gains rate which comes out to just under 28% so his own lifetime earnings is probably around $360 million.