One game for $500 million? What a waste, no way.
Instead I would gather the best developers of western point & click adventures (Ron Gilbert, Tim Schaefer, Roberta Williams, The Two Guys from Andromeda, Charles Cecil, Jane Jensen, Al Lowe, the former Westwood Studios guys who developed Kyrandia, the Telltale/Deck13/Pendulo/Quantic Dreams crews and others).
I'd tell these people that they can make 100 point & click adventures with 2D graphics and that the overall costs of each game are limited to exactly $4.9 million.
As I'd know in advance that these games won't make any profit, I'd secretly keep the remaining $10 million.