🚀 Space Battle

🎮 How to play

Reach the goal score before you run out of lives. Shoot the aliens, dodge their bombs, and don't let any reach the bottom.

• ◀ ▶ buttons or ← →: Move your ship.
• Fire button or the space bar: Shoot. You can only have a few shots in the air at once.

⚙️ Your functions

You write these functions. The game calls them when something happens.

• onHit()

  Runs every time you destroy an alien.

  function onHit() {
    score = score + 10;
  }

• onDamage()

  Runs when a bomb hits you or an alien reaches the bottom.

  function onDamage() {
    lives = lives - 1;
  }

• onWave(n)

  Runs when you wipe out a whole wave. n is the number of the wave you just beat.

  function onWave(n) {
    // a bonus for beating a wave?
  }

🎚️ Settings you can change

Variables at the top of your code are the game's settings. Change a value, press Play, and see what happens.

ship = "🚀"

Your ship.

alien = "👾"

The invaders.

goal = 100

Reach this score to win.

lives = 3

Hits you can take.

speed = 2

From 1 (slow) to 5 (fast).

maxBullets = 3

How many of your shots can be flying at once (1 to 6).

danger = 0.1

From 0 to 1: how often the aliens drop bombs. 0 means never.

wave = 1

The current wave. The game counts it up for you. set by the game

bullet = "🔹"

The emoji for your shots. optional

bomb = "💣"

The emoji for alien bombs. optional

score = 0

Your points. The game starts it at 0 and you change it in your functions. set by the game

🪜 Step by step

Each step shows code you can add to the end of your game's code. A function or variable written later replaces the earlier one, so you never have to delete anything.

1. 1Play the starter

   Move under the aliens and fire. Each alien you destroy runs onHit.

   function onHit() {
     score = score + 10;
   }

2. 2More firepower

   Allow more shots at once, and make the aliens drop fewer bombs.

   let maxBullets = 5;
   let danger = 0.05;

3. 3Armour that takes two hits

   A counter can make a rule apply only some of the time. Here you only lose a life on every second hit, because the first one just dents your armour.

   let hits = 0;
   
   function onDamage() {
     hits = hits + 1;
     if (hits % 2 === 0) {
       lives = lives - 1;
     }
   }

4. 4A bigger magazine each wave

   onWave gets the wave number n, and you can change any setting there. Here each wave you beat scores 100 and lets you have one more shot in the air at once (up to 6).

   function onWave(n) {
     score = score + 100;
     maxBullets = Math.min(6, maxBullets + 1);
   }

// 🚀 Space Battle!
let ship = "🚀";
let alien = "👾";
let goal = 100;         // reach this score to win
let lives = 3;
let speed = 2;         // 1 (slow) to 5 (fast)
let maxBullets = 3;    // how many shots can be flying at once
let danger = 0.1;        // 0 to 1: how often aliens drop bombs

function onHit() {
  score = score + 10;
}

function onDamage() {
  lives = lives - 1;
}

// n is the wave you just beat
function onWave(n) {
  // a bonus for beating a wave?
}

💡 Ideas to try

• A bug-zapper: a 🕷️ ship against 🐛 aliens.
• A bullet-hell mode: danger 0.6 with 6 lives.
• Make each wave pay double what the last one did.

Tips

• Aliens march sideways and step down at the edges. Take them out from one side first.
• Waves get bigger each time, so save your shots for good targets.

🎓 Lessons for this game

• 🔒Space Battle: first blastPremium
• 🔒Space Battle: shieldsPremium
• 🔒Space Battle: wave bonusPremium