Interactive game access code form | HTML, CSS & JavaScript

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

body {
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: #000;
    color: #fff;
    overflow: hidden;
}

/* 🌌 PARTICLE BACKGROUND */
#bgCanvas {
    position: fixed;
    inset: 0;
    z-index: -1;
}

/* CONTAINER */
.container {
    text-align: center;
    width: 380px;
    padding: 20px;
    background: rgba(255, 255, 255, 0.03);
    backdrop-filter: blur(10px);
    border-radius: 24px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

h2 {
    margin-bottom: 20px;
    letter-spacing: 2px;
    text-transform: uppercase;
    font-size: 1.2rem;
    color: #00f7ff;
}

/* PROGRESS */
.progress {
    height: 4px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 10px;
    margin-bottom: 30px;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, #00f7ff, #6c63ff);
    transition: width 0.3s ease;
}

/* OTP INPUTS */
.otp-box {
    display: flex;
    justify-content: space-between;
    gap: 10px;
}

.otp-box input {
    width: 50px;
    height: 65px;
    border-radius: 12px;
    border: 1px solid rgba(108, 99, 255, 0.4);
    background: rgba(20, 20, 25, 0.8);
    color: #fff;
    text-align: center;
    font-size: 24px;
    font-weight: bold;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    outline: none;
}

.otp-box input:focus {
    border-color: #00f7ff;
    background: rgba(108, 99, 255, 0.1);
}

/* STATE CLASSES */
.filled {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px -3px rgba(0, 247, 255, 0.2);
    border-color: #00f7ff !important;
}

.error input {
    border-color: #ff4d4d !important;
    animation: shake 0.4s focus;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

/* POPUP */
.popup {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.9);
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.5s ease;
    z-index: 100;
}

.popup.show {
    opacity: 1;
    pointer-events: auto;
}

.popup-box {
    background: #111;
    padding: 40px;
    border-radius: 20px;
    border: 1px solid #00f7ff;
    text-align: center;
    transform: scale(0.8);
    transition: transform 0.3s ease;
}

.popup.show .popup-box {
    transform: scale(1);
}

.btn-retry {
    margin-top: 20px;
    padding: 10px 25px;
    background: #6c63ff;
    border: none;
    color: white;
    border-radius: 8px;
    cursor: pointer;
}
p {margin-top: 20px; font-size: 0.8rem; color: #555;}
/* EXPLOSION PARTICLES */
#particles {
    position: fixed;
    inset: 0;
    pointer-events: none;
}

.particle {
    position: absolute;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    animation: explode 1s forwards cubic-bezier(0, 0.5, 0.5, 1);
}

@keyframes explode {
    to {
        transform: translate(var(--x), var(--y)) scale(0);
        opacity: 0;
    }
}

const canvas = document.getElementById("bgCanvas");
const ctx = canvas.getContext("2d");
let stars = [];

function resize() {
    canvas.width = window.innerWidth;
    canvas.height = window.innerHeight;
}
resize();
window.addEventListener("resize", resize);

for (let i = 0; i < 150; i++) {
    stars.push({
        x: Math.random() * canvas.width,
        y: Math.random() * canvas.height,
        size: Math.random() * 1.5,
        speed: Math.random() * 0.8 + 0.1
    });
}

function animateBg() {
    ctx.fillStyle = "rgba(0, 0, 0, 0.2)";
    ctx.fillRect(0, 0, canvas.width, canvas.height);

for (let s of stars) {
        s.y += s.speed;
        if (s.y > canvas.height) s.y = 0;
        ctx.fillStyle = "#00f7ff";
        ctx.beginPath();
        ctx.arc(s.x, s.y, s.size, 0, Math.PI * 2);
        ctx.fill();
    }
    requestAnimationFrame(animateBg);
}
animateBg();

/* OTP LOGIC */
const inputs = document.querySelectorAll(".otp-box input");
const progress = document.getElementById("progress");
const otpBox = document.getElementById("otpBox");
const popup = document.getElementById("popup");
const title = document.getElementById("title");
const particleContainer = document.getElementById("particles");

const CORRECT_OTP = "123456";

// Auto-focus first input
inputs[0].focus();

function updateProgress() {
    let filled = [...inputs].filter(i => i.value).length;
    progress.style.width = (filled / 6) * 100 + "%";
}

inputs.forEach((input, index) => {
    // Handle typing
    input.addEventListener("input", e => {
        const val = e.target.value;
        if (!/^[0-9]$/.test(val)) {
            input.value = "";
            return;
        }

input.classList.add("filled");
        if (index < inputs.length - 1) inputs[index + 1].focus();
        
        updateProgress();
        checkOTP();
    });

// Handle Backspace
    input.addEventListener("keydown", e => {
        if (e.key === "Backspace") {
            if (!input.value && index > 0) {
                inputs[index - 1].focus();
                inputs[index - 1].value = "";
                inputs[index - 1].classList.remove("filled");
            } else {
                input.classList.remove("filled");
            }
            updateProgress();
        }
    });

// Handle Paste
    input.addEventListener("paste", e => {
        e.preventDefault();
        const data = e.clipboardData.getData("text").slice(0, 6);
        if (!/^\d+$/.test(data)) return;

data.split("").forEach((char, i) => {
            if (inputs[i]) {
                inputs[i].value = char;
                inputs[i].classList.add("filled");
            }
        });
        updateProgress();
        checkOTP();
    });
});

function checkOTP() {
    let otp = [...inputs].map(i => i.value).join("");

if (otp.length === 6) {
        if (otp === CORRECT_OTP) {
            createExplosion();
            setTimeout(() => showPopup("SYSTEM OVERRIDE SUCCESSFUL", "Welcome back, Commander."), 500);
        } else {
            otpBox.classList.add("error");
            // Vibrate effect for mobile
            if(navigator.vibrate) navigator.vibrate(200);
            
            setTimeout(() => {
                inputs.forEach(i => {
                    i.value = "";
                    i.classList.remove("filled");
                });
                otpBox.classList.remove("error");
                inputs[0].focus();
                updateProgress();
            }, 600);
        }
    }
}

function showPopup(t, m) {
    popup.classList.add("show");
    title.innerText = t;
    document.getElementById("msg").innerText = m;
}

function createExplosion() {
    const colors = ["#00f7ff", "#6c63ff", "#ffffff"];
    for (let i = 0; i < 60; i++) {
        const p = document.createElement("div");
        p.className = "particle";
        p.style.left = "50%";
        p.style.top = "50%";

const angle = Math.random() * Math.PI * 2;
        const velocity = 100 + Math.random() * 200;
        
        p.style.setProperty("--x", Math.cos(angle) * velocity + "px");
        p.style.setProperty("--y", Math.sin(angle) * velocity + "px");
        p.style.background = colors[Math.floor(Math.random() * colors.length)];

particleContainer.appendChild(p);
        setTimeout(() => p.remove(), 1000);
    }
}

- Interactive game access code form

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