We will create a "native" Unity3D AdDuplex plugin in the near future, but it's still possible and easy to integrate AdDuplex into a Unity game. Here are a couple of tutorials:
- How-to: Integrate AdDuplex into a Unity3d game
- How to integrate AdDuplex banner into your Unity game (part 1)
- How to integrate AdDuplex banner into your Unity game (part 2)
You can also use AdRotator Unity plugin to implement AdDuplex as well as other ad providers into your Unity game.