A much faster alternative to the QGIS built in 2.5D style. It simulates 3D from a point above the center of the map, presenting objects gradually more oblique towards the map edges. You control the effect by a single value in the "Offset" data defined override. If you have buildings with the elevation as an attribute value, you can use this to control the effect with an expression in stead of a simple value. (Designed for projected layers with the same project CRS)