c++ – SImple pet caring game – console

I’m a beginner programmer and i’m looking for interesting projects to improve my low skills. I tried one day to improve my skills by trying to create a small game in which a user owns a cat, and has to feed it and clean it. My main aim of the game(which yet has many illogical things like the never decreasing happiness and cleanness level) was to try and keep my code as clean and presentable as possible. The game is made in 4 different files, and I will paste them all below. I will be happy if anyone could give me help on understanding where should I improve.

Lets go into the code:

main.cpp

#include "Cat.h"
#include "pet game.h"
#include <iostream>
using namespace std;

int main() {
    //Create the user's profile
    //User();

    //Welcome messages
    cout
            << "Welcome to Unga bonga! Here you buy pets and raise them as your kids, and try to level up, in order to finish the game!"
            << endl;
    showHelp();

    //Command execution
    do {
        commandIdentify();
    } while (true);
}
Cat cat;
//User user;

void showHelp() {
    cout << "The commands in this game are:" << endl
            << "1. to feed your cat, type f" << endl
            << "2. to clean your cat, type c" << endl
            << "3. to check your cat's happiness, type h" << endl
            << "4. to check your cash balance, type m" << endl
            << "5. to check your level status, type l" << endl
            << "6. to display this help message, type ?" << endl
            << "7. to exit, type e" << endl
            << "8. Finally, to play this game, enjoy!" << endl;
}
    
void commandIdentify() {
    //take input
    cin >> command;
    //identify and execute
    switch (command) {
    case 'f':
        feedCat();
        break;
    case 'c':
        cleanCat();
        break;
        case 'h':
         checkHappiness();
         break;
    case '?':
        showHelp();
        break;
    case 'e':
        exit();
    default:
        cout << "That's not a command -yet (probably)" << endl;
    }
}

void feedCat() {
    cout << "Time for food!!!" << endl;
    cat.feed();
}

void cleanCat() {
    cout << "Let's take a bath!!!" << endl;
    cat.clean();
}

void checkHappiness(){
 cat.checkHappiness();
 }

int exit() {
    exit(0);
    return 0;
}

pet game.h:

    #ifndef PET_GAME_H_
#define PET_GAME_H_

#include <iostream>
#include "Cat.h"
//#include "User.h"

using namespace std;

//Global variables
char command;
int exit();

//functions
void commandIdentify();
void buyNextCat();
void showHelp();
void tutorial();
void feedCat();
void cleanCat();
void checkHappiness();

//functions defined for a future use but they cause problems right now
void checkMoney();
void checkLevel();


#endif /* PET_GAME_H_ */

Cat.cpp:

#include <iostream>
#include <string>
#include "Cat.h"

using namespace std;

Cat::Cat(){
    happiness = 1;
    cleanness = 1;
}

void Cat::feed(){
    cout << "Yummy!!" << endl;
    Cat::happiness = Cat::happiness + 0.2;
}

void Cat::clean(){
    cout << "So soupy!!" << endl;
    Cat::cleanness = Cat::cleanness + 0.2;
}

Cat.h:

#ifndef CAT_H_
#define CAT_H_

#include <iostream>

using namespace std;

class Cat {
private:
    int happiness;
    bool happy = happiness >= 0.6;

    int cleanness;
    bool isClean = cleanness >= 0.6;
public:
    Cat();
    void feed();
    void clean();
    void checkHappiness() {
        cout << "Your cat's happiness is " << happiness*100 << "%" << endl;
    }

};

#endif /* CAT_H_ */

it will be great if you could tell me how to improve code