This first person controller was made because there aren't many first person controllers for Godot, and the ones that do exist are pretty bad. It is highly customizable and comes with many features, QOL, and clean code.

Some parts came from StayAtHomeDev's FPS tutorial. You can find that here.

Directions

Move with WASD, space to jump, shift to sprint, C to crouch.

FEATURES:

In-air momentum
Motion smoothing
FOV smoothing
Head bobbing
Crouching
Sprinting
2 crosshairs/reticles, one is animated (more to come?)

If you make a cool game with this addon, I would love to hear about it!

Wiki

To start out, you should probably remap all of the movement keys to your own control set.
You can make this a super basic controller by just disabling everything.

How to change settings:

Click on the character node and there should be settings in the "Feature Settings" group.

How to add animations for a mesh:

In the _physics_process function, add a line to check whether you are walking or aren't walking. You can do this by checking whether input_dir is true or false. Optionally, set the animation speed to speed / base_speed. This will make it so when the player is walking, your animation speed is 1. If the player is sprinting, your animation goes up and if the player is crouching your animation speed goes down.

In the toggle_sprint function, add a line at the end where if is_sprinting is true, your animation is set to sprint.

In the toggle_crouch function, add a line where if is_crouching is true, your animation is set to crouch.

To check if the player is in the air, add a line in the _physics_process function where it says if not is_on_floor():set your animation to falling/in the air. Add an else statement to change it to the normal state.

How to change reticles (crosshairs):

Find the folder at res://addons/fpc/reticles
Pick one and add it to the UserInterface node in the character scene. You may need to right click on the character and enable "Editable Children".
Set the Character value to your character node (it's under the Nodes group)
Change the anchors_preset value on the reticle to Center

How to create a new reticle

Choose a reticle to base it off of
Open that reticle and save it as a new reticle
Edit the reticle to your needs
Follow the "how to change reticles" directions to use it