Score
0
Lives
Level
1
Best
0

Online Space Invaders

Select difficulty to begin

Controls
  • ← → move ship
  • Space shoot
  • Mouse Click aim & shoot
  • P pause
  • F fullscreen

Paused

Press Space or P to continue

Game Over

Score: 0
Best: 0
Difficulty
Medium
Controls
Mouse
Tags: Game
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Space Invaders is a fast arcade shooter where you clear waves of descending enemies while managing limited lives and chasing a higher score. Many players enjoy the feel of a classic arcade shooter as levels speed up and the field grows busier.

You choose a difficulty, then move, aim, and fire to carve lanes through the formation. Your score climbs as enemies disappear, and the next wave arrives once the current grid is cleared. You can pause anytime to catch your breath and resume when ready.

Controls are simple so attention can stay on timing and position. The keyboard gives predictable movement and the mouse offers fine aim, so switching between them can help in tight moments. The best runs come from patient positioning rather than constant firing.

A typical round starts easy and becomes busier as rows increase, so it pays to watch the edges and plan exits before the grid steps down. If the formation drops past your ship’s row you lose a life, and the round ends when lives are gone.

For consistent results, pick one difficulty and practice short bursts, use fullscreen for clarity, and pause if you need to reset focus.

Technical Details:

The experience tracks three quantities that define progress and pressure: score in points, lives as a count, and level as the current wave. Pressure rises when the grid steps down toward the ship and when horizontal speed increases between levels.

Each defeated invader adds points to the score, and clearing the grid advances the level while nudging enemy speed upward. Lives define your margin for error, so the main decision is how aggressively to thin the front row without letting the sides wrap you in.

Difficulty changes the baseline pace. Easy favors learning, Normal balances pace and control, and Hard demands quicker choices from the first moments. Results vary with timing and aim, not chance, so repeat runs on the same difficulty are comparable.

The playfield is a fixed world with left, right, top, and bottom bounds; the grid moves horizontally and steps down when it touches a side. Collisions use axis‑aligned checks on object bounds, and identical inputs produce the same outcomes aside from cosmetic randomness in shapes and colors.

vₓ(L) = v₀+ 0.002·(L−1) rows(L) = L+2 score = 10·kills
Symbol Meaning Unit/Datatype Source
vₓ(L) Invader horizontal speed at level L world units per frame Derived
v₀ Baseline horizontal speed from difficulty world units per frame Input
rows(L) Row count in the current wave integer Derived
kills Invaders eliminated in the wave or run integer Derived

Worked example

vₓ(3)= 0.010+0.002·(3−1)=0.014
rows(3)=3+2=5
score=10·35=350

On Normal at level 3 you face five rows and earn 10 points per defeat; clearing all 35 yields 350 points.

Difficulty Bullet speed (units/frame) Baseline invader speed (v₀) Speed increment per level
Easy 0.10 0.008 +0.002
Normal 0.12 0.010 +0.002
Hard 0.15 0.020 +0.002
Parameter Meaning Unit/Datatype Value Notes
Lives Starting life count integer 3 Shown as hearts in the HUD.
Score per invader Points for each defeat integer 10 Accumulates across levels.
Columns Invaders per row integer 7 Constant across levels.
Rows Grid height integer L + 2 One extra row each level.
Vertical step Downward move on wall hit world units 0.12 Triggers when the grid touches a side.
Bounds Playfield limits (left, right, top, bottom) world units −5, 5, 5, −5 Ship and grid are clamped to this area.
Shoot cooldown Minimum frames between shots frames 12 Clicking faster does not increase fire rate.
  1. Initialize scene, camera, renderer, and static starfield.
  2. Spawn the ship at the lower center and attach input listeners.
  3. Create the invader grid with colored shapes in rows and columns.
  4. On each frame, update movement, bullets, invaders, particles, and HUD.
  5. Reverse and step the grid down when it reaches a side boundary.
  6. Detect bounds intersections; award points and remove defeated invaders.
  7. Advance level when the grid is empty; increase horizontal speed.
  8. Deduct a life if the grid drops below the ship; end when lives reach zero.

Privacy & compliance — Processing is browser‑based with no server calls or account storage. Gameplay has no monetary value.

How‑to · Step‑by‑Step Guide

Space Invaders aims to clear each wave while preserving lives and building score.

  1. Select a difficulty Easy, Normal, or Hard.
  2. Move with the arrow keys and fine‑tune aim with the mouse.
  3. Fire with Space or left click; pace shots to keep lanes open.
  4. Watch the sides; when the grid touches a wall it steps downward.
  5. Pause with P to regroup; toggle fullscreen with F for clarity.
  6. Clear the grid to level up; adapt to the faster pace.

Example — On Normal, clear five rows at level 3; a full wave of 35 defeats yields 350 points.

  • Pro tip: carve a central channel, then pick off flankers before the next step down.

Features:

  • Three difficulties that tune bullet and enemy speed.
  • Keyboard movement with mouse aim and click‑to‑fire.
  • Clean HUD with score, lives, and level indicator.
  • Escalating waves with one extra row each level.
  • Fullscreen toggle and pause overlay for focus.
  • Colorful shapes, soft lighting, particles, and starfield backdrop.

FAQ:

Is my data stored?

No. The game runs locally and does not save accounts, scores, or personal information.

No server communication or persistence.
How accurate is hit detection?

Hits are based on axis‑aligned bounds. It favors clarity and speed, so edge cases may feel generous or strict.

Consistent within a run and across devices.
What units do speeds use?

Speeds are in world units per frame. Frame pacing is managed by the display refresh cycle.

Numbers are comparable within the same device.
Can I play offline?

Yes, once assets are loaded, gameplay works without a network connection.

Reloading may require cached assets.
What does difficulty change?

It sets baseline enemy speed and bullet speed. Each new level still increases enemy speed by a fixed amount.

Wave height also increases by one row per level.
How do I go fullscreen?

Press F or use the fullscreen button in the corner. Press F again or Esc to exit.

Some browsers require a user gesture.
Do enemies fire back?

No. The challenge is the descending formation and its lateral pressure.

Speed increases across levels.
Why did firing stop?

A short cooldown limits shots. Wait a moment before firing again.

The cooldown is measured in frames.

Troubleshooting:

  • If keys do not respond, click the play area to regain focus.
  • If fullscreen fails, check browser permissions and user‑gesture requirements.
  • Stutter on low‑power devices improves by closing other heavy tabs.
  • Pointer aim off by a little? Recenter the mouse and avoid fast window resizes.
  • Very small windows reduce playfield clarity; enlarge or use fullscreen.
  • Muted colors usually indicate display night‑modes; disable for accurate contrast.
  • Alerts pause play; dismiss them to continue.
  • Touchscreens may register taps as clicks; a mouse is recommended.

Advanced Tips:

  • Work the lowest row to slow the step‑down and buy time.
  • Keep a central escape lane so you can shift sides quickly.
  • Fire in short bursts to avoid over‑committing before a side reversal.
  • Use pause to plan the next two steps, not just the next shot.
  • Watch for the wall; every touch predicts a downward step.
  • If the grid is low, prioritize clearing a vertical channel.

Glossary:

HUD
On‑screen display for score, lives, and level.
Wave
One grid of invaders to clear before leveling up.
Cooldown
Minimum frames between consecutive shots.
Bounds
Edges that limit ship and grid movement.
AABB
Axis‑aligned bounding‑box method for hit checks.
Baseline speed
Starting grid speed set by difficulty.