/!\ NOTICE /!\As of Blender 2.63.0 (Official stable release available on the Blender site) the core mechanics of Blender have been greatly improved. Blender now supports single faces that have more than 4 or 3 edges/vertices called "n-gons". So for example an octagon with 8 vertices and 8 edges could be a single face. Before you would have needed to construct this octagon from 8 or 6 triangles or 3 quads.From left to right: A triangle "tri", a square "quad", an octagon "8-gon" (single face!), and an octagon constructed of 3 quads.Obviously these n-gons are not supported in Blockland but they are not supported in any older versions of Blender either. This new feature is called BMesh and it completely reworked the entire polygon modeling aspect of Blender. This also affects the .blend saves.In order to open .blend files saved in Blender 2.63 or newer with older Blender versions you need to save the file again with Legacy Mesh Format. Please note that this gets rid of all ngons in the save.To save with Legacy Mesh Format, go to File > Save As... or press Ctrl + Alt + S and check/tick the Legacy Mesh Format checkbox.The .blend file you just saved will now open in old Blender versions.
