AO is combined from prebaked AO, made by OGSE developers and realtime AO with some colorbleeding for bright areas.
actually, i dont understand why some mordern game titles dont use prebaked occlusion maps? It provides rly soft shadowing for big volumes, with literally no impact on player-side. However alot of work is meant to be performed on developer side ( yea... those lasy bit***s )
And realtime AO can be limited for only close area around player, so we can have more depth percision for local and dynamic lighting on actors.
i dont mean, that xray have cool approach for prebaked AO (its not that good as it might sound), however for almost 0 performance cost, its an awesome technique