Hello!
Windows Mixed Reality Portal is a new tool included in the latest version of Windows 10 Insiders. Another one for the Holographic Windows platform toolset.
Note: To test this app you need Build 15048 or higher.
So, the best way to test this tool is to have one of the new Windows Holographic compatible devices (e.g. Acer MR Headset). In the meantime, but we can try it out using a Simulator features, a keyboard and optionally an XBox Controller.
These are the steps to launch the Simulator
1. Search for the “Mixed Reality Portal” App
2. Launch the App
3. I am writing this from an “old PC” and this one does not pass the minimum requirements to run the App. 
4. No problem, let’s use the Simulation mode
5. Let’s start to learn on the features inside this App.
After I’ve used the app for a while, I’ll highlight a couple of interesting details:
- We have the Start Menu of Windows 10 we know of Hololens
- The app XBox seems to me that we can play in virtual/mixed environments, broadcasting from our XBox One.
- I think simulation environment is the same “core” Hololens, we can see that only apps can be active at the same time 3.
- This is important, we have the app for Windows 10 Connect that allows us to connect other devices via Miracast. This means that we can “project” our smartphone, another computer, etc within the virtual world! (link)
At this moment, I found a video that shows all the step by step in 7 minutes and I think that it’s worth seeing it!
Greetings @ Toronto
El Bruno
References
El Bruno 