7. Mirrors and glass

You will first create another corridor starting from the second room.
Switch to Select Mode,

in the Top View, select the corridor linking the two rooms and clone it by holding the Shift key and drag and drop it.
The Top View should look like this:

Click on the Scale Brush button,

and scale the corridor in X axis as shown below, in the Top View:

You will now make an opening between the second room and the new corridor.
Click on the Scale Brush button again to return in Select Mode, and select the Cut brush between the first corridor and the second room. In the Top View, hold the Shift key and drag and drop the selected Cut brush as shown below.

You will now create a window frame on the same wall, next to our door frame.
Lock the Z axis by clicking on the Lock Z button,

hold the Shift key and drag and drop the Cut brush on the left, along the wall.
Click on the Scale Brush button,

in the Side View, scale up the bottom of the window frame.

Unlock the Z axis by clicking the Lock Z button and return in Select Mode by clicking the Scale Bush button again.
Lock the X axis with the Lock X button.

In the Top View, clone the window frame (hold the Shift key and drag and drop the brush), click on the Scale Brush button and in the Top View, scale the brush as thick as the wall as shown below. Then, unlock the X axis and click on the Scale Brush button.

Click on the Face/Brush Attributes button and change the Type from Cut to Window.

Switch to Face Mode by pressing the Page Down key, and click on the Face/Brush Attributes button. Check the Transparent box and enter a Transparency Value of 100.

Return in Brush Mode by pressing the Page Down key again.
You need some light in this corridor. Select the light inside the second room and clone it into the corridor.

You just created a glass window. Now let's transform the end of the corridor in a mirror. Select the new corridor and switch to Face Mode (Page Down key). Press the Left Arrow key until the face at the end of the corridor is selected.

Click on the Face/Brush Attributes button, check the Mirror box, the Transparent box and enter a Transparency Value of 20.

Switch back to Brush Mode by pressing the Page Down button.
Compile and run.
 

From the new corridor, you can see, through the window, the door from the second room opens with 2 Bots chasing you.

You can see yourself in the mirror.