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🛸 Void Sentinel

Click to place · 1-5 select tower · Space to start wave · Click tower to upgrade/sell

Void Sentinel — Free Online Tower Defense Game

Void Sentinel is a free browser-based sci-fi tower defense game. Alien invaders are streaming through a fixed corridor toward your base — place towers along the path to intercept and destroy them before they break through. Start with basic Pulse turrets and work your way up to devastating Rail guns and chain-lightning Tesla coils. No download, no sign-up — just open the page and play unblocked.

Each wave brings tougher enemies: fast Scouts, armored Tanks, tiny Swarms that overwhelm your defenses, and massive Bosses every five waves. Earn credits from every kill to build new towers and upgrade existing ones. The key to survival is smart placement — combine slowing Cryo emitters with high-damage Plasma cannons, or cover the entire path with Tesla chains.

How to Play

Controls

  • Click an empty cell to place the selected tower type.
  • 1-5 keys to switch tower type (or tap the bottom bar).
  • Space (or tap Start button) to launch the next wave.
  • Click an existing tower to select it, then U to upgrade or S to sell.
  • Right-click or Escape to deselect.

Tower Types

  • Pulse ($50) — Balanced turret with medium range and fire rate.
  • Plasma ($100) — Slow-firing splash damage in a wide radius.
  • Cryo ($75) — Slows enemies and nearby targets. Low damage but invaluable.
  • Tesla ($125) — Chain lightning jumps to 3 nearby enemies.
  • Rail ($150) — Long-range sniper. Devastating single-target damage.

Tips & Strategy

Placement Matters

Towers placed at corners of the path get the most value — enemies spend more time in range as they turn. Place Cryo towers early in the path to slow enemies into the kill zone of your damage dealers further along.

Upgrade vs. Expand

A single level-3 tower is often more efficient than three level-1 towers. Upgrading increases damage by 40% per level and slightly boosts range and fire rate. Save up for upgrades on your best-positioned towers.

Boss Waves

Every 5th wave spawns a Boss with massive HP. Make sure you have strong single-target damage (Rail guns) ready. Bosses that reach the end cost 5 lives instead of 1 — let one through and it could end your run.