How would I add a cheat code to a title screen

Raptorkillz Okay but in the code there's this line

Yeah, but there are other lines as well

Here's an automatic class that listens to action sequences, and when it finds something, it notifies about that via a signal:

class_name CheatCodeListener extends Node
signal code_entered(name)
var s: String
var cheats  = {"ui_up ui_down ui_up" : "some cheat", "ui_left ui_right" : "some other cheat"}

func _input(e):
	for a in InputMap.get_actions().filter(func(aa): return e.is_action_pressed(aa)).slice(0,1):
		s += a if not s else " " + a
		for k in cheats.keys(): if s.contains(k): code_entered.emit(cheats[k]); s = ""

Now the only thing left to do is to make a game to cheat at. Easy peasy

Raptorkillz Okay but how would I make it play a sound

print(String.chr(0x07)). But you'll need to start a console version of Godot for this to work.

trizZzle Konami cheat in a SEGA game? Is this allowed?

I don't think so. But this thread already entered the psychoactive zone, and while passing the threshold it may have created an alternate reality in which this is not only allowed but is in fact - mandatory.

Raptorkillz That addon works with keys, not with actions.
I wrote you the complete thing. Just connect the signal and do whatever you want (play sound etc...) in the signal handling function. If you don't understand what I'm talking about, you really need to go through the introductory tutorial I mentioned earlier.

Raptorkillz Of course it isn't because you're connecting the signal after it's been emitted. You need to do it beforehand. Put the connect call in _ready() or connect it manually in the inspector.

Raptorkillz Use a simpler cheat code for testing and put a print statement in the signal handler to see it it's getting called. Also make sure you don't have multiple actions mapped to the same input because the script will use only the first mapped action it finds in the InputMap.
Btw you have too much whitespace in your code.