The Game Dev version can be installed as an update :
(it will look for your existing PP2014 installation)

But is is a complete version that comes with a full PoserPro2014 version,
upgraded to SR4, and all content and support files.

Default :
It will uninstall your current PP2014 installation.
Install the new PP2014 Game Dev version build 10.0.4.27796, with the new support and content files.

Then you go to the Help menu => Personalise
=> input your new serial number to activate the Game Dev functions
Restart Poser.

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But If you choose : You can install to another folder on your PC.
I can not see why?
As the new version is PP2014 SR4 , AND unlocks to the Game Dev version by its new serial number.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!