ULTROS!
People seem to like me because I am polite and I am rarely late. I like to eat ice cream and I really enjoy a nice pair of slacks.
Tri-Ace is also using Unreal Engine 4, which probably cut down on development time.
They make their own engines, they don't use external engines.
Here's their latest engine (2011, maybe being used for SO5): https://www.youtube.com/watch?v=AnVtG4XYKHE