A 2D tower defense game built with vanilla JavaScript, HTML5 Canvas, and Electron.

• ES modules — source organized in src/ with clean module boundaries
• Canvas 2D rendering — game world drawn on HTML5 Canvas, with canvas overlays plus DOM panels for settings/help
• Electron desktop app — packaged with electron-builder (NSIS), auto-updates via GitHub Releases
• 12 troop types — melee, ranged, splash, chain lightning, siege, Ice Wizard (splash + slow + shatter), Healer (support healing + monster damage), and Flamer (melee burn DoT)
• 9 monster types — Grunt, Runner, Brute, Elite, Champion, Necromancer, Shielded, Boss, Spear
• Modernized icon — redesigned tower icon with glowing beacon and vibrant gradients
• Slow & Shatter — Ice Wizard slows enemies (50% speed, 2.5s); next hit on slowed target deals +50% bonus damage. Splash 1.5 tiles applies slow to all hit monsters.
• Three monster attack modes — stop (default, pauses to attack), slow (slows near troops, attacks while moving), pass (penetration, hits each troop once)
• Troop HP — troops have health pools and can be destroyed by monsters
• Upgradeable troops — 4 independently upgradeable stats per troop (DMG / RNG / SPD plus type-specific stats), up to level 5 each; Lightning adds CHN, Healer adds TGT, Ice Wizard adds SLW
• Dev mode (triple-click gold) — infinite gold & lives, custom wave composition via dedicated DEV popup. Start Wave button is greyed out in dev mode (use DEV popup to launch custom waves)
• Adjustable game speed — 1x / 2x / 4x / 8x / 16x / 32x / 64x / 128x
• Background heartbeat — keeps the main-thread sim running when the window is backgrounded
• Auto-update — built-in update checker via GitHub Releases with channel selection (stable / pre-release)
• Notification system — bell icon with toast popups, notification panel with action buttons
• Settings panel — persistent settings with Save/Cancel, update channel selection, check interval
• About page — game info, version, and GitHub repo link
• Animated tray windows — smooth roll-up/down transitions, only one tray window open at a time
• Pause menu — DOM-based modal with Resume, Restart, and Save Game buttons; backdrop click does not resume (must use Resume button); ESC resumes when paused; focus trap keeps Tab within menu buttons; canvas gets aria-hidden when menu is open
• Title screen — canvas background with animated gradient and twinkling particles; DOM overlay with New Game, Load Game, Settings, and About buttons; click anywhere or press SPACE to start; respects prefers-reduced-motion
• Smart cursor — standard arrow by default, hand pointer on clickable elements (shop, buttons, troops, grid)
• 16x16 grid with procedurally generated winding paths
• Necromancer — revives dead allied monsters within range (up to 4 per Necromancer); revived monsters take 50% reduced damage
• Monster splitting — non-Boss, non-Shielded, non-pass-mode monsters split into 2 of level-1 on death (e.g. Champion → 2 Elite)
• Sell confirmation — 30% refund with 3-second global cooldown

Upgradeable stats per troop:

• All troops: DMG (×1.2 per level), RNG (ranged only, +1 tile/level), SPD (×0.9 per level, faster)
• Lightning: also CHN (+1 chain target per level)
• Flamer: also BRN through DMG upgrades; higher damage increases burn tick damage and displayed burn DPS
• Healer: also TGT (more simultaneous heal targets); deals 3 damage to monsters in heal range
• Ice Wizard: also SLW (stronger slow, longer duration, bigger shatter per level)
• Melee troops take 70% reduced damage from monster attacks

Boss HP is doubled at spawn (3336 effective) and passively heals 15 HP/s. Necromancers revive dead allies within 2-tile range (up to 4 per Necromancer); revived monsters become reviveImmune and take 50% reduced damage. Non-Boss, non-Shielded, non-pass-mode monsters split into 2 of level-1 on death (e.g. a Brute spawns 2 Runners; a Champion spawns 2 Elites).

Monsters have three attack modes:

• stop (default): Stops moving when a troop is in range, attacks, then resumes. Used by Grunt, Brute, Elite, Champion, Boss, Shielded.
• slow: Moves at normal speed when no troop is nearby. Slows to half speed when a defense troop is in range and attacks the closest one. Used by Spear.
• pass: Always moves at full speed. Deals damage to troops while passing — each troop is hit at most once (penetration). Used by Runner.

Troops have HP and can be destroyed — plan your defenses carefully!

Melee troops take 70% less damage from monster attacks — they are your front line. Ranged troops take full damage and must be protected.

• Starting gold: 1000
• Max gold: 1,000,000
• Starting lives: 25
• Sell refund: 30% of total gold invested, rounded up
• Upgrade costs: round(base × 1.35^(level-1)) (1→2: base cost, 2→3: 1.35× base, 3→4: 1.82× base, 4→5: 2.46× base)

The bottom bar contains buttons for all in-game panels:

When the game is paused (Space), a DOM-based modal overlay appears with three buttons:

Clicking the backdrop does not resume the game — the player must click the Resume button or press Space/ESC. The pause menu includes a focus trap that keeps Tab/Shift+Tab cycling within the menu buttons, and the game canvas receives aria-hidden="true" so screen readers focus on the modal dialog.

When the game starts or the player returns to the title screen, a canvas background with an animated gradient and twinkling particles is displayed, overlaid with a DOM modal. The quick access bar (Monsters, Controls, DEV, Settings, Notifications, About) is hidden during the title screen and only appears once the player starts the game.

Settings are edited in draft mode and only persisted when you click Save (or discarded with Cancel). The Save and Cancel buttons are fixed at the bottom-right of the settings popup, remaining in the same position regardless of which tab is active.

• Update channel: Choose between Release (stable only) or Pre-release (beta, alpha, rc)
• Auto-download: When enabled, updates download automatically after confirmation
• Check interval: How often to check for updates (15–120 minutes)
• Check Now: Manually trigger an update check
• Save / Cancel: Persist or discard changes; settings survive reinstalls

The audio settings panel has been simplified to a single Master volume slider with live percentage display. Individual SFX, Ambient, and UI volume sliders and mute toggles have been removed for a cleaner, less cluttered interface.

• Toast popups appear in the bottom-right corner and fade away after a few seconds
• Notification panel (bell icon) shows all notifications with timestamps
• Action buttons appear inline for actionable notifications:
  • Update available → Update / Cancel
  • Download complete → Restart & Install
• Click any notification in the panel to replay its toast
• Notifications stack newest on top, oldest on bottom

Displays the game name, version with release type (e.g. v1.7.2), author (AvCode-exe), and a clickable link to the GitHub repository.

The game checks for updates on startup (configurable) and offers to download them:

1. Check — queries GitHub Releases for the latest version matching your channel
2. Notify — if an update is found, a toast appears and the notification panel shows Update/Cancel buttons
3. Download — clicking Update starts the download with a progress bar at the bottom of the screen
4. Install — when complete, click Restart & Install to apply the update

Channel selection:

• Release — only stable releases (e.g. v1.2.0)
• Pre-release — includes beta, alpha, and RC builds (e.g. v1.6.0-beta.2)

Settings persist across reinstalls via %USERPROFILE%\.tower-defense\settings.json.

• ES modules — source organized in src/ with subdirectories for rendering and UI modules
• Vanilla JavaScript (ES6+) — no frameworks, game world rendered on canvas with DOM panels for configuration/help
• HTML5 Canvas 2D rendering with devicePixelRatio scaling and offscreen canvas caching
• Background heartbeat — keeps the main-thread simulation running at full speed when the window is backgrounded (all actual simulation, AI, and rendering still happen on the main thread)
• Electron 42 desktop app with electron-builder (NSIS)
• electron-updater for auto-update via GitHub Releases
• Vitest — unit + integration test suite (1,938 tests, 50 files, 92.93% branch coverage)
• Performance benchmarks — 50 hot-path benchmarks across 15 engine areas (tile index, monster index, combat, AoE, projectiles, waves, particles, Healer, economy, state helpers) in tests/benchmarkHotPaths.test.js
• ESLint — static code analysis for bug detection and code quality
• Prettier — consistent code formatting across all source files

The codebase follows consistent patterns for maintainability:

• Tile-index spatial lookups — O(1) neighbor queries via _monsterTileIndex and _troopTileIndex, with a shared monstersInRange() helper eliminating scan duplication
• Data-driven particle effects — all 9 effect types defined in a single EFFECT_DEFS table with identical configs, spawned via a generic _spawnEffect() dispatcher
• Config-driven design — all game tuning constants, monster specs, troop specs, and wave definitions live in config.js
• Entity pooling — projectiles, popups, and tile-index arrays are recycled to minimize GC pressure
• Offscreen canvas caching — static grid/path layers rendered once to offscreen canvases
• Path2D caching — troop rounded-rectangle paths created once and reused across frames
• Expanded test coverage — dedicated coverage for UI helpers, UI constants, input mapping, audio effects, renderer transforms/cache behavior, toast notifications, cursor hit-testing, and release-feed parsing
• Fixed-timestep simulation — deterministic game logic decoupled from frame rate via accumulator
• Zero-allocation coordinate helpers — _into variants (tileCenterInto, pixelToTile, shopCardRectInto) write into pre-allocated output objects
• 6 performance optimizations applied:
  • Troop index dirty flag — _buildTroopTileIndex() deferred until troops actually change (~36× faster cleanup, 97% reduction)
  • Monster tile index swap-remove — O(n) indexOf+splice replaced with O(1) tracked-position swap-remove
  • monstersInRange scratch buffer — per-call array allocation eliminated via game-owned reusable buffer
  • _tmpCfg reuse — particle config object allocation eliminated per effect spawn
  • Healer scratch buffer — Healer _tryHealAllies per-frame array allocation eliminated
  • Pending-attack queue — _stepMonsterAttacks no longer scans all monsters; drains a collected queue instead

src/
  main.js            # App entry point
  game.js            # Core game loop and state
  gameRuntime.js     # Runtime execution and wave orchestration
  config.js          # Game constants and tuning values
  grid.js            # 16x16 grid management
  troop.js           # Troop definitions, upgrades, and combat
  monster.js         # Monster AI, pathfinding, splitting, and attack modes
  projectile.js      # Projectile logic (bullets, chains, splash)
  waveManager.js     # Wave spawning and progression
  pathGenerator.js   # Procedural path generation
  particles.js       # Data-driven particle effects with pooling
  audio.js           # Sound management
  input.js           # Keyboard and mouse input
  gamePersistence.js # Save/load game state
  updateManager.js   # Auto-update logic
  utils.js           # Shared helpers
  rendering/
    renderer.js      # Core Canvas 2D renderer
    gameRenderer.js  # Game-specific rendering (troops, monsters, projectiles)
  ui/
    index.js         # UI module aggregator
    hud.js           # Heads-up display (gold, lives, wave info)
    shop.js          # Troop shop panel
    shieldShop.js    # Shield shop panel
    overlays.js      # Win/lose overlays
    placement.js     # Troop placement logic
    preview.js       # Troop preview on hover
    toast.js         # Toast notification system
    constants.js     # UI layout constants
    utils.js         # UI helper functions
tests/
  helpers.js              # Shared test utilities (makeGame, makeTileIndex, longPath, etc.)
  config.test.js          # CONFIG, MONSTER_SPECS, TROOP_SPECS, WAVES validation
  grid.test.js            # Grid and TILE constants
  utils.test.js           # Utility functions (clamp, lerp, dist, pixelToTile, etc.)
  pathGenerator.test.js   # Procedural path generation
  projectile.test.js      # Projectile logic
  particles.test.js       # Particle effects
  game.test.js            # Core game: canPlace, placeTroop, sellTroop, upgrades, combat
  gameRuntime.test.js     # Runtime loop, pause render loop, resize, and state transitions
  monster.test.js         # Monster constructor, AI, combat, splitting, necromancer, shatter
  monsterIntegration.test.js # Monster spawning, movement, lifecycle, mixed interactions
  troop.test.js           # Troop stats, upgrades, healing, shield, healer, chain lightning
  persistence.test.js     # Save/restore serialization, game world factory
  waveManager.test.js     # Wave queue, necromancer shuffling, custom waves, preview
  updateManager.test.js   # Auto-update filtering, settings, electron integration
  integration.test.js     # End-to-end: melee/ranged combat, selling, upgrading, game speed
  combatIntegration.test.js # Troop-specific combat: splash, chain, mortar, knight, sniper
  goldEconomy.test.js     # Economy: costs, refunds, upgrades, shields, kill rewards
  performance.test.js     # Performance: step throughput, entity scaling, memory stability
  memoryLeak.test.js      # Memory: entity lifecycle, pool recycling, long sessions
  devMode.test.js         # Dev mode economy and spawn mechanics
  placementPreview.test.js # Placement preview DPS/HPS calculations
  versioning.test.js      # Beta release versioning logic
  githubReleaseFeed.test.js # GitHub Atom feed parsing
  uiUtils.test.js         # UI rounded rect, tooltip, text wrapping, toggle hit tests
  uiConstants.test.js     # UI layout constants and color tokens
  input.test.js           # Mouse, wheel, context menu, and keyboard input mapping
  audio.test.js           # AudioManager context, volume, mute, and SFX node chains
  renderer.test.js        # Canvas renderer init, resize, transforms, and static layers
  toast.test.js           # Toast creation, classes, click removal, and timers
  gameRendererCursor.test.js # Cursor hit-testing for UI, troops, placement, and dialogs
  pauseMenu.test.js         # Pause menu and title screen DOM integration tests
  smoke.test.js           # Installer smoke test (entry points, file existence)
electron-main.js     # Electron main process
preload.cjs         # Electron preload script (CommonJS for sandbox compat)
index.html          # Single-page canvas host
css/                # Minimal styles (tray windows, notifications)

The app stores data in the following locations:

Details:

• ~\.tower-defense\settings.json — primary settings file. Persists across reinstalls so your update channel, auto-download preference, and check interval are remembered.
• %APPDATA%\tower-defense\settings.json — backward-compatibility copy of settings (written alongside the persistent copy).
• %APPDATA%\tower-defense\game-save.json — in-game save data (troops, waves, gold). Deleted when you start a new game.
• %APPDATA%\tower-defense\logs\ — Electron-generated log files (auto-created).
• %LOCALAPPDATA%\tower-defense-updater\ — cache for downloaded update installers, managed by electron-updater.

To do a clean reset, delete the .tower-defense folder in your user profile and the tower-defense folder in %APPDATA%.

npm install          # Install dependencies
npm start            # Run in dev mode
npm run build        # Build NSIS installer (dist/Tower Defense Setup X.X.X.exe)
npm run release      # Build + publish to GitHub Releases (requires GH_TOKEN)
npm run lint         # Check code for bugs and issues
npm run lint:fix     # Auto-fix lint issues
npm run format       # Reformat all code with Prettier
npm run format:check  # Check formatting without modifying files
npm test             # Run test suite (1,938 tests)
npm run test:watch   # Run tests in watch mode
npm run test:coverage # Run tests with code coverage report
npm run test:bench    # Run performance hot-path benchmarks (50 tests)

Apache 2.0 — see LICENSE for details.