How to install:

Download and unzip the .py file. 

In Blender, go to Edit>Preferences>Keymap

At the top of the keymap, is an import button. Press it and navigate to the .py file that you want to use and install it.

How to Install AP Navigation

Summary of changes to the keymap:

All keymaps include WASD navigation. If not noted here, assume default Blender keymap:

apNavBlender.py

This keymap is the Blender defaults, with the only real difference being the navigation. Best for people who prefer Blender over game engine shortcuts, but want to be able to navigate similar to your game engine of choice. 

-To navigate, you click and hold the right mouse button and while holding, press WASD to move forward/left/back/right.

-To move down/up, click and hold right mouse button and while holding, press Q/R

-You can increase/decrease walk speed by holding right mouse button and scrolling middle mouse up/down

-To Pan, use middle mouse button (instead of shift + middle mouse button)

-To orbit, use alt left mouse button (instead of middle mouse button)

-To right click, hold alt+right mouse button

-g,s,r remain normal.

-F to frame selected

apNavGameEngine.py

This keymap is more similar to game engine than Blender. It's best for people who prefer game engine style shortcuts like W,E,R to move, rotate, scale. 

-To navigate, you click and hold the right mouse button and while holding, press WASD to move forward/left/back/right.

-To move down/up, click and hold right mouse button and while holding, press Q/R

-To Pan, use middle mouse button (instead of shift + middle mouse button)

-To orbit, use alt left mouse button (instead of middle mouse button)

-To extrude in edit mode, press cntl + E

-To "Frame Selected" (otherwise known as focus), press F (instead of "numpad .")

-To grab, press W and use the Gizmo (instead of  G)

-To rotate, press E and use the Gizmo (instead of R)

-To scale, press R and use the Gizmo (instead of S)

-Q is disabled to work better for navigating (default it quick shortcuts)

-To right click, hold alt+right mouse button