I have been able to create the functioning game however sometimes It will ask to tap flag for say " Nigeria" but none of the options of flags to choose will include the correct flag. Other times it will have the right flag included.

Thank you in advance.

Share your code :)

//
//  ContentView.swift
//  guessflags
//
//  Created by Josh on 9/24/22.
//

import SwiftUI

struct ContentView: View {

    @State private var showingScore = false
    @State private var scoreTitle = ""
    @State private var userScore = 0
    @State private var testArray = ["Omg","Achmed", "Persey"]
    @State private var gamesPlayed = 0
    @State private var gameIsReset = false

    func resetGame() {
        if gamesPlayed == 8 {
            userScore = 0
            gamesPlayed = 0
            print("resetting game! Eight games played!")
        }
        else {
            print("keep playing")
        }
    }

    func flagTapped (_ number: Int) {
        if number == correctAnswer {
            scoreTitle = "Correct!"
            userScore = userScore + 1
        } else {
            scoreTitle = "Wrong! thats the flag of \(countries[number])"
        }
        showingScore = true
        gamesPlayed = gamesPlayed + 1
        resetGame()

    }

    func askQuestion() {
        countries.shuffle()
        correctAnswer = Int.random(in: 0...3)
    }

    // properties to store game data
    @State private var countries = ["Estonia", "France", "Germany", "Ireland", "Italy", "Nigeria", "Poland", "Russia", "Spain", "UK", "US"].shuffled()

    @State private  var correctAnswer = Int.random(in: 0...3)
    var body: some View {

//        LinearGradient(gradient: Gradient(colors: [.blue, .black]), startPoint: .top, endPoint: .bottom)
//            .ignoresSafeArea()

        ZStack {

            RadialGradient(stops: [
                .init(color: Color(red: 0.1, green: 0.2, blue: 0.45), location: 0.3),
                .init(color: Color(red: 0.76, green: 0.15, blue: 0.26), location: 0.3),
            ], center: .top, startRadius: 200, endRadius: 400)
                .ignoresSafeArea()

            VStack {
                Spacer()
                Text("Guess the flag").font(.largeTitle.weight(.bold)).foregroundColor(.white)

            VStack (spacing: 15){

                Text("Tap the flag of").font(.subheadline.weight(.heavy)).foregroundColor(.secondary)
                Text(countries[correctAnswer]).font(.largeTitle.weight(.semibold))

                //loop to show flags as buttons
                ForEach(0..<3) {number in
                    Button {
                  flagTapped(number)

                    } label: {
                        Image(countries[number])
                            .renderingMode(.original).clipShape(Capsule()).shadow(radius: 5)
                    }
                }
            }.frame(maxWidth: .infinity)
                .padding(.vertical, 20)
                .background(.regularMaterial)
                .clipShape(RoundedRectangle(cornerRadius: 20))
                Spacer()
                Text("Score is \(userScore)").foregroundColor(.white)
                Spacer()
            }
            //this alert runs if state change in showingscore
            .alert(scoreTitle, isPresented: $showingScore) {
                Button("Continue", action: askQuestion)
            } message: {
                Text("Your score is \(userScore) and games played are \(gamesPlayed)")
            }.alert("Reset the game", isPresented: $gameIsReset) {
                Button("Continue", action:resetGame)
            }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()

    }
}

}

Check this,

func askQuestion() {
        countries.shuffle()
        correctAnswer = Int.random(in: 0...3)
    }

You are asking to ask a question for 4 case , 0,1,2 & 3 But, your Button label is

ForEach(0..<3) {number in

Update the Int.Random to 0..2 and you should be ok.