The engine in this case is the game engine - a huge bit of software to determine player placement, in-game physics calculation (for jumping, flying, ballistics, etc), and graphics apportionment (Unreal uses "zones" to determine on-the-fly rendering quality of each area within a map, coupled with on-the-fly field-of-depth rendering as well...) There is one other thing I neglected to mention as a possible downer as well - the Unreal Engine is limited in the number of polygons it can handle at any one time, according to the player's set FOV. I haven't looked at the specs for this engine, but Unreal Tournament 2003 was limited to 10,000 polys per animated model (assuming a set-piece animation and not in-game rendering), which would mean that Vicky 3 would choke in a hurry unless someone, somewhere did something to improve the game engine by a sizeable percentage. /P