To us, ID@Xbox is about providing a level playing field for all developers. So, we worked with Unity and we’re pleased to announce that, when released in 2014, the Xbox One add-on for Unity will be available at no cost to all developers in the ID@Xbox program, as will special Xbox One-only Unity Pro seat licenses for Xbox One developers in the ID@Xbox program.
The Unity add-on for Xbox One supports every element of Xbox One, from Kinect to SmartGlass to the impulse triggers of the new controller. Using Unity, developers will be able to take advantage of all aspects of Xbox One, which is rad. More importantly, Unity is available for Windows and Windows Phone too (and yes, the add-on is available at no cost to developers for Windows Phone and Windows 8 store games). So from one base game, developers can ship their games across all Microsoft platforms.
usually, unity pro costs $1500, then each platform pro add on usually costs another $1500 each. pro license and addon is free for id@xbox devs, and for windows 8 and windows phone,you have to pay the $1500 pro fee,but both addons are free.