>free AAA game engine
Doesn't being called that require that there are AAA games developed with it? According to wikipedia,
"In the video game industry, AAA (pronounced "triple A") or Triple-A is a classification term used for games with the highest development budgets and levels of promotion or the highest ratings by a consensus of professional reviewers."
So if it's an engine for games with highest development budgets, why would they care about the engine being free? Clearly choosing a free engine is a cost-saving measure, at which point you're no longer making an AAA game by definition.