Unity Cookie - 2D Space Shooter

Creating a 2D Space Shooter – 2D Toolset Introduction
With the introduction of Unity 4.3 an entirely dedicated 2D toolset has been added. Prior to this version, 2D development within Unity was very cumbersome and relied on 3D features that were unnecessary and sometime inefficient for 2D development. But with the addition of the 2D toolset, Unity has removed all those issues of developing 2D projects within Unity.
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Url : http://cgcookie.com/unity/cgc-courses/creating-2d-space-shooter-2d-toolset-introduction/