```xml
<?xml version="1.0" encoding="UTF-8"?>
<game>
  <title>UFO Alien Shooter</title>
  <slug>ufo-alien-shooter</slug>
  <short-desc>Defend against alien UFOs in this HTML5 space shooter! Blast invaders, dodge fire, and aim for the high score. Features diverse enemies and sound.</short-desc>
  <categories>
    <category>Shooter</category>
    <category>Arcade</category>
    <category>Sci-Fi</category>
  </categories>
  <keywords>UFO, alien, shooter, space game, arcade, HTML5, canvas, retro, invaders, defense, spaceship, classic movies</keywords>
  <content>
# About UFO Alien Shooter

Welcome to UFO Alien Shooter, an action-packed HTML5 space shooter where you pilot Earth's last defense against a relentless alien invasion. Take control of your advanced starfighter, inspired by classic designs, and blast waves of incoming UFOs descending from the cosmos.

Face a diverse armada of extraterrestrial threats, each with unique designs and behaviors reminiscent of iconic sci-fi movie craft. Encounter Standard saucers, swift Arrowheads, tricky Zigzagging Spinners, heavily armored Tanks, and projectile-firing Tripod Shooters. The invasion intensifies as your score climbs, with UFOs spawning more frequently and moving faster, pushing your piloting and shooting skills to the limit.

With responsive keyboard, mouse, and touch controls, immersive sound effects that bring the battle to life, and a dynamic starry background, UFO Alien Shooter offers a thrilling arcade experience. Your mission is clear: destroy as many aliens as possible, protect your 15 lives, and achieve the ultimate high score!

## How to Play

**Objective:** Your primary goal is to shoot down as many alien UFOs as possible to earn points. You must also avoid colliding with UFOs or their projectiles and prevent them from reaching the bottom of the screen.

**Controls:**
*   **Movement:** Use the `Arrow Left`/`A` key and `Arrow Right`/`D` key to move your spaceship horizontally. On touch devices or with a mouse, you can click/touch and drag your ship to position it.
*   **Shooting:** Press the `Spacebar` to fire your ship's cannons. On touch devices or with a mouse, tap/click anywhere on the game screen (except on your ship itself) to shoot. There's a brief cooldown (300ms) between shots.

**Lives:** You begin the game with 15 lives. A life is lost if:
*   Your ship collides with a UFO.
*   Your ship is hit by a UFO's projectile.
*   A UFO successfully passes your defenses and reaches the bottom of the screen.

**UFO Types:** Be prepared to encounter various UFOs, each with different characteristics:
*   **Standard:** Classic saucer, moves steadily with some horizontal drift.
*   **Fast:** Arrowhead design, moves quickly downwards.
*   **Zigzag:** Spinner design, moves in an oscillating pattern.
*   **Tank:** Heavily armored, moves slower but can shoot.
*   **Shooter:** Tripod design, moves with some horizontal drift and shoots frequently.

**Scoring:** Destroying different types of UFOs awards varying amounts of points.
*   Standard: 10 points
*   Fast: 20 points
*   Zigzag: 25 points
*   Shooter: 35 points
*   Tank: 50 points

**Game Over:** The game ends when you run out of lives. Your final score will be displayed, and you'll have the option to restart.

**Progression:** As your score increases, UFOs will begin to spawn more frequently (spawn interval decreases) and their base speed will gradually increase, heightening the challenge.

## Features

-   **Diverse Alien Fleet:** Battle five unique types of UFOs (Standard, Fast, Zigzag, Tank, Shooter), each with distinct visual designs, movement patterns, points, and attack capabilities (for Tank and Shooter types).
-   **Responsive Multi-Platform Controls:** Enjoy smooth gameplay with keyboard (Arrow Keys/A/D for movement, Space for shooting), intuitive mouse controls (drag ship to move, click off-ship to fire), and full touch support for mobile devices.
-   **Dynamic Difficulty Curve:** The game's challenge progressively increases with your score, featuring faster UFO spawns and slightly increased enemy speeds, keeping you on your toes.
-   **Immersive Soundscape:** Experience the action with engaging sound effects for player shots, UFO explosions, player hits, enemy fire, and game over events, powered by Howler.js.
-   **Classic Arcade Action:** Relive the excitement of retro space shooters with modern HTML5 technology, complete with a scrolling starfield background that adds to the cosmic atmosphere.
-   **Adaptive Visuals:** The game dynamically resizes its canvas and elements to fit your browser window or device screen for an optimal playing experience.
-   **Detailed Ship Designs:** Pilot a uniquely designed player starfighter and face off against creatively crafted alien vessels.

## Controls

**Keyboard:**
*   `Arrow Left` or `A` key: Move your spaceship to the left.
*   `Arrow Right` or `D` key: Move your spaceship to the right.
*   `Spacebar`: Fire your spaceship's weapon.
*   `Spacebar` or `R` key (when game is not active): Start or restart the game.

**Mouse:**
*   **Move:** Click and drag your spaceship to move it horizontally.
*   **Shoot:** Click anywhere on the game screen (except on your spaceship) to fire.
*   **Start/Restart:** Click when prompted on the message overlay to start or restart the game.

**Touchscreen:**
*   **Move:** Touch and drag your spaceship to move it horizontally.
*   **Shoot:** Tap anywhere on the game screen (except on your spaceship) to fire.
*   **Start/Restart:** Tap when prompted on the message overlay to start or restart the game.

## Tips & Strategies

-   **Prioritize Dangerous Targets:** Focus on eliminating Tank and Shooter UFOs first, as they are the only ones that fire back. Zigzag UFOs can be unpredictable, so deal with them before they get too close.
-   **Master Defensive Movement:** Don't just stay in one spot. Constant, controlled movement makes you a harder target for both UFOs and their projectiles. Learn to weave between enemy fire.
-   **Efficient Firing:** Your ship has a 300ms firing cooldown. Make your shots count, especially against faster or more evasive targets. Avoid simply holding down the fire button; aim your shots.
-   **Learn UFO Patterns:** Each UFO type has a distinct movement behavior. Observe these patterns to better anticipate their paths and position yourself for effective shots and dodges.
-   **Use the Full Screen Width:** Maneuver across the entire available space to create distance and find better angles, but be cautious not to get trapped at the edges as UFO density increases.
  </content>
  <faq>
    <question>How do I save my progress in the game?</question>
    <answer>This game is session-based. Your score and progress are tracked for the current game. High scores are not saved between sessions in this version.</answer>
    
    <question>Can I play this game on mobile devices?</question>
    <answer>Yes, this game is fully compatible with mobile browsers and supports touch controls.</answer>
    
    <question>Is this game free to play?</question>
    <answer>Yes, the game is completely free to play in your browser.</answer>
  </faq>
  <specifications>
    <multiplayer>false</multiplayer>
  </specifications>
</game>
```

An interactive game created with AI assistance