A lot of stuff originally developed for Mafia will be used in other Illusion games, like our physics, cut scene editor, etc. Our engine enables us to use huge outdoor areas and also indoors, without any loss of quality in each part. But the beauty of the graphics is not in the number of polygons. It's in our graphic artists, especially our lead artist Pavel Cizek. But our programmers are also very hard working people.
Many engines have trouble rendering large outdoor areas and detailed interiors.
Well we had some experience with our previous engine, so when we decided to develop a new one, we knew how to solve a few things. But most of the time, we were just redesigning the graphics again and again to fit into the limits of our engine and to produce enough quality. We tried to copy as much from the real world as possible . A lot of people are afraid about that, because the games they have played from a 3rd person view were ugly, characters had strange animations, or controls were uncomfortable. The creation of good game from 1st person is much easier, because you only have to model the weapons.