Posted onJul 4

State Machine Explained Like You’re 5

#statemachine #gamedev #godot

What’s a State Machine?

What if I ask you, what is the name of this game above?

It's Mario

Okay, now let's imagine you’re playing Mario. Mario can:

Stand
Throw fireballs
Run
Jump
Do nothing (idle)
Die

But he can’t do all of them at the same time. Mario’s “state” decides what he’s doing right now.

That is where state machines come in handy:

A state machine is just a system that:

Knows what state it’s in (standing, running, jumping…)
Knows how to switch between states (e.g., press jump → Mario jumps)
Doesn’t let you do illegal stuff (e.g., you can’t throw fireballs while dying)

How Does It Work?

The most popular example used while explaining state machines is the Traffic Light.

Think of a traffic light :

Green → Yellow → Red
It’s not random. You don’t go Green → Green → Red → Red → Yellow.
Each state only allows certain transitions.
You can't be in 2 states at one time.

Same in games:

Can Mario jump from "Dying"? Nope.
Can an enemy attack while "Dead"? Nope.

That’s the beauty of a state machine.

Why NOT Just Use If-Else?

if player.is_jumping:    # Jump logicelif player.is_running:    # Run logicelif player.is_dead:    # Death logic

Looks cool right now, look at this.

SOURCE ARTIFICIAL INTELLIGNECE, CODE NOT MEANT TO BE RUN ITS JUST FOR EXAMPLE

class Player:    def __init__(self):        self.is_idle = True        self.is_running = False        self.is_jumping = False        self.is_shooting = False        self.is_dead = False        self.is_crouching = False        self.is_falling = False        self.is_attacking = False    def update(self, inputs):        if self.is_dead:            print("Play death animation")            # Game Over logic            return        if inputs.get("press_jump"):            if self.is_crouching:                print("Can't jump while crouching... but wait it still happens!")            self.is_jumping = True            self.is_idle = False            self.is_running = False            print("Jumping...")        if inputs.get("press_run"):            if self.is_jumping:                print("Running mid-air like Naruto (why?)")            self.is_running = True            self.is_idle = False            print("Running...")        if inputs.get("press_crouch"):            if self.is_jumping:                print("Crouching mid-air. This isn’t Fortnite bro.")            self.is_crouching = True            self.is_idle = False            print("Crouching...")        if inputs.get("press_attack"):            if self.is_dead:                print("Attacking while dead? Ghost attacks?")            else:                self.is_attacking = True                print("Attacking!")        if inputs.get("fall_detected"):            if self.is_running:                print("Falling while running? Sure why not.")            self.is_falling = True            print("Falling...")        # Reset states randomly (why? because spaghetti)        if inputs.get("landed"):            self.is_jumping = False            self.is_falling = False            self.is_idle = True            self.is_running = False            self.is_attacking = False            self.is_crouching = False            print("Landed. Reset everything!")player = Player()# Simulate random inputsinputs = {    "press_jump": True,    "press_run": True,    "press_crouch": True,    "press_attack": True,    "fall_detected": True,    "landed": False}player.update(inputs)

In this code:

You can run, crouch, jump, attack, AND fall at the same time.
No clear “current state” — it’s just flags all over.
Adding ONE more state means more if-else hell.
Debugging? I would rather not respond to that.

Now, let's say you usea state machine

SOURCE ARTIFICIAL INTELLIGENCE, CODE NOT MEANT TO BE RUN IT'S JUST FOR EXAMPLE

class State:    def enter(self, player):        pass    def exit(self, player):        pass    def handle_input(self, player, inputs):        passclass IdleState(State):    def enter(self, player):        print("Mario is now standing still (Idle)")    def handle_input(self, player, inputs):        if inputs.get("press_run"):            player.change_state(RunningState())        elif inputs.get("press_jump"):            player.change_state(JumpingState())        elif inputs.get("press_crouch"):            player.change_state(CrouchingState())        elif inputs.get("press_attack"):            player.change_state(AttackingState())        elif inputs.get("die"):            player.change_state(DeadState())class RunningState(State):    def enter(self, player):        print("Mario starts running 🏃‍♂️")    def handle_input(self, player, inputs):        if inputs.get("release_run"):            player.change_state(IdleState())        elif inputs.get("press_jump"):            player.change_state(JumpingState())        elif inputs.get("press_attack"):            player.change_state(AttackingState())        elif inputs.get("die"):            player.change_state(DeadState())class JumpingState(State):    def enter(self, player):        print("Mario jumps into the air 🦘")    def handle_input(self, player, inputs):        if inputs.get("landed"):            player.change_state(IdleState())        elif inputs.get("die"):            player.change_state(DeadState())class CrouchingState(State):    def enter(self, player):        print("Mario crouches 👀")    def handle_input(self, player, inputs):        if inputs.get("release_crouch"):            player.change_state(IdleState())        elif inputs.get("die"):            player.change_state(DeadState())class AttackingState(State):    def enter(self, player):        print("Mario attacks 🔥")    def handle_input(self, player, inputs):        if inputs.get("attack_done"):            player.change_state(IdleState())        elif inputs.get("die"):            player.change_state(DeadState())class DeadState(State):    def enter(self, player):        print("Mario has died 💀")    def handle_input(self, player, inputs):        pass  # No transitions from Deadclass Player:    def __init__(self):        self.state = IdleState()        self.state.enter(self)    def change_state(self, new_state):        self.state.exit(self)        self.state = new_state        self.state.enter(self)    def update(self, inputs):        self.state.handle_input(self, inputs)# Example usageplayer = Player()inputs = {    "press_run": True}player.update(inputs)inputs = {    "press_jump": True}player.update(inputs)inputs = {    "landed": True}player.update(inputs)inputs = {    "die": True}player.update(inputs)

In this code: