I tried to find a precise definition. I found clues on Wikipedia and on Gaming SE, but I cannot find more than an approximation like:
Equivalent of blockbuster movie in cinema, an AAA game is a game with highest development budgets and levels of promotion.
The definition seems imprecise. How can I be sure a game is AAA?
Let's imagine a small indie studio making games and growing up. They hire more and more people through the years and invest more and more money in their game. At which milestone would their game be considered as AAA?