Gravedigger.io – The Nightshift — Deep Dive Strategy Guide

Overview / Game Introduction

Gravedigger.io – The Nightshift is a single-file, zero-dependency first-person zombie wave-defense game that runs entirely in your browser. Built by eons2eons as an experimental AI-generated project with Claude, the entire game — procedural graveyard, six-weapon combat system, escalating waves, synthesized audio, and HUD — is contained in a single index.html file. No install, no server, no asset downloads.

You are the gravedigger on the night shift. The dead aren't staying buried tonight. Zombies rise from tombstones in a procedurally generated graveyard, and your job is to survive as many waves as possible. There is no final wave, no ending — the horde keeps coming until you fall.

Target audience: Fans of classic browser FPS games, zombie wave-defense enthusiasts, and anyone who appreciates technical marvels (the entire game is one HTML file). If you've played and enjoyed The House of the Dead, Killing Floor's survival mode, or even Call of Duty Zombies, the escalating pressure will feel familiar.

Unique angle: This game was produced from a single AI prompt. The entire codebase, all weapon mechanics, enemy AI, procedural generation, and audio synthesis were created in one shot with follow-up review passes. It's a fascinating case study in AI game development AND a genuinely fun wave shooter.

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Getting Started — First 10 Minutes

How to Launch

Open index.html in any modern desktop browser with WebGL + Web Audio support (Chrome, Firefox, Edge, Safari). You can either:

• Clone the GitHub repo and open the file locally.
• Play directly on itch.io.

Your First Shift — Step by Step

1. Press "BEGIN THE SHIFT" on the title screen. The graveyard generates fresh — terrain, tombstones, trees, lanterns, and the mausoleum are all procedurally placed.

2. Wave 1 starts immediately — 5 slow zombies rise from the ground near tombstones. They move toward you at a randomized speed (1.35–2.5 units/second).

3. Use the shovel — it's a one-hit kill with a 0.46-second swing cooldown and infinite ammo. No reload, no ammo management. Walk toward a zombie, press Space when it's within 2.55 units, and it dies instantly.

4. Find the pistol — weapon pickups glow on the ground. During wave 1, use the lull to locate the pistol (usually near the starting area). This is your backup.

5. Survive wave 1 — with only 5 zombies, this is essentially a tutorial. Once all 5 are down, you get a 4.2-second break before wave 2.

Beginner Mistakes to Avoid

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Core Mechanics Explained

Health & Regeneration System

Your health bar sits at the bottom-left of the HUD:

• Max HP: 100 (5 hits from a zombie at 20 damage each)
• Regeneration trigger: 4.2 seconds without taking damage
• Regeneration rate: 4 HP per second
• Visual cues: Red flash on hit → pulsing red vignette when critically low

Strategic implications: Between waves, you have a 4.2-second break. This is exactly enough time to trigger health regen. If you finish a wave at 60 HP, kite the remaining zombies for 5 seconds before re-engaging. Let the regen top you off.

The Wave System — Exponential Scaling

Each wave follows the formula: 5 × 2^(wave−1) zombies.

The soft cap: The game limits how many zombies can be alive simultaneously (base 5 + 2 per wave, max 20 at wave 8+). This keeps performance smooth, but the TOTAL zombies per wave still counts — zombies queue up and spawn as you kill them. You cannot "clear" a wave by outrunning the spawns; you must kill every zombie in the wave before the next one starts.

Weapon System — Stats & Analysis

Six weapons, each with a specific role:

Assault Rifle breakdown: 28 damage per shot × 0.11s fire rate = ~255 DPS. Range of 72 units with low spread makes it effective at any distance. Most zombies die in 4 shots. This is your primary weapon from wave 5 onward.

Shotgun damage math: 19 damage × 8 pellets = 152 max damage per shot if all pellets hit. At close range (under 12 units), this kills most zombies in a single blast. The wide spread means damage falls off quickly at range — get close.

Gatling Gun math: 22 damage × 20 rounds/second = 440 DPS. The highest raw damage output in the game. The tradeoff: 2.6-second reload ties you to one spot for longer than you can safely stand still in high waves. Use it ONLY when cornered or during a wave break for cleanup.

Ammo Economy

• 10 ammo crates spawn across the map initially.
• Each crate auto-refills ALL guns you're carrying.
• Crates respawn 26 seconds after being picked up.
• At 10 crates, you can theoretically refill every 2.6 seconds if you cycle between them.

Ammo conservation rules:

• Waves 1–2: Shovel only. Save ammo.
• Waves 3–5: Pistol + Shotgun. Conserve assault rifle ammo.
• Waves 6+: Assault rifle primary, SMG secondary. Shotgun for emergencies.
• Wave 8+: Gatling gun comes out. Burn ammo freely — you either survive or die.

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Progression Strategy

Early Game (Waves 1–3) — Gear Up

Objective: Stock weapons while the pressure is low.

1. Wave 1: Shovel only. Locate the pistol and at least one ammo crate.
2. Wave 2: Grab the pistol. Practice weapon swap (T) and reload (R).
3. Wave 3: Find the shotgun and/or SMG. Locate the assault rifle if you can.
4. Do NOT pick up the gatling gun yet — it takes a valuable weapon slot and its reload is crippling this early.

Mid Game (Waves 4–6) — Hold Chokepoints

Objective: Establish defensive positions and manage multiple weapons.

1. Locate the mausoleum. Its narrow entrance creates a natural chokepoint — zombies can only approach single-file.
2. Stand at the mausoleum entrance with the shotgun. One blast clears the entrance.
3. When the shotgun runs dry, switch to the assault rifle for cleanup.
4. Circle the perimeter — don't stand still in the open. Use WASD to strafe around the graveyard's outer edge.
5. Watch the soft cap: at wave 4, only ~13 zombies can be alive at once. Kill fast enough and new ones spawn immediately.

Late Game (Wave 7+) — Pure Survival

Objective: Maximize DPS and never stop moving.

1. Primary: Assault Rifle. Its combination of damage (28), fire rate (0.11s), range (72), and low spread make it the undisputed best weapon.
2. Secondary: SMG for crowd thinning or Shotgun for close emergencies.
3. Tertiary: Gatling Gun — only when you have a clean escape route after emptying the mag.
4. Shovel stays in your inventory forever. Use it to finish stragglers and conserve ammo.
5. Never let your back face an open area. Zombies rise from tombstones — keep your back to a wall or the mausoleum.

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Step-by-Step Strategy — 7 Actionable Sequences

Sequence 1: Wave 1 — Scavenge Run

1. BEGIN THE SHIFT.
2. Immediately look around — identify nearby weapon pickups (glowing objects on the ground).
3. Kill the first 2-3 zombies with the shovel (one-hit each, 0.46s swing).
4. While the remaining zombies approach, jog to the nearest weapon pickup.
5. Grab the pistol. Check its ammo count.
6. Kill the remaining wave 1 zombies with the shovel or pistol.
7. During the 4.2-second break, locate ammo crates and weapon pickups. Memorize their positions.

Sequence 2: Mausoleum Hold (Waves 4–6)

1. During the wave 3 → 4 break, move to the mausoleum.
2. Verify: shotgun is loaded and in your active slot.
3. As wave 4 starts, position yourself at the mausoleum entrance.
4. When zombies approach the entrance single-file, blast the first one with the shotgun.
5. Immediately switch to the assault rifle. Pick off approaching zombies from range.
6. When they get close (under 15 units), switch back to the shotgun.
7. Cycle weapons: Shotgun for chokepoint → Assault Rifle for ranged → SMG for mid-range.
8. If health drops below 60 HP, retreat through the mausoleum and kite zombies around it.
9. Let regen activate (4.2s without damage), then re-engage.

Sequence 3: Perimeter Patrol (Any Wave)

1. Instead of staying in one spot, move in a large circle around the graveyard's edge.
2. Keep the graveyard on one side of your field of view — zombies can only approach from one direction.
3. As you circle, pass by previously memorized ammo crate locations.
4. Pick up ammo as you pass — this keeps all guns topped off without dedicated ammo runs.
5. Kill approaching zombies with the assault rifle at range (60+ units) before they get close.
6. If the perimeter becomes crowded, cut through the center to the opposite side.
7. The key advantage: zombies never surround you if you're circling the edge.

Sequence 4: Ammo Cycling (Resource Management)

1. Memorize the positions of all 10 ammo crates.
2. Assign each crate a mental "zone" (North, East, South, West graveyard).
3. When any weapon reaches 50% reserve ammo, path toward the nearest crate in your next zone.
4. Pick up the crate — it refills ALL guns simultaneously.
5. Never let the assault rifle drop below 120 reserve (50% of 240).
6. If you're on the shotgun and below 24 reserve, switch to the SMG until you reach a crate.
7. Ammo crates respawn in 26 seconds — by the time you circle back, they'll be ready again.

Sequence 5: Health Crisis Recovery

1. Screen flashes red → you've been hit. Immediately disengage.
2. If HP is 80+: keep fighting but be more cautious.
3. If HP is 40–60: fall back to the mausoleum or the far side of the graveyard.
4. Use the shovel to kill pursuing zombies (one-hit kill, no ammo cost).
5. Once no zombies are within attack range (wait 5 seconds), health regen activates.
6. At 4 HP/second, you go from 40 HP to full in 15 seconds.
7. After full recovery, re-engage with ranged weapons first.

Sequence 6: Gatling Gun Emergency Protocol

1. Activate ONLY when: (a) you're cornered with 20+ zombies approaching, OR (b) wave 8+ and you need to thin the horde fast.
2. Switch to gatling gun. Fire in controlled bursts (1–2 seconds each).
3. 100 rounds at 20 rounds/second = 5 seconds of continuous fire.
4. After 3 seconds of firing, start looking for your escape path.
5. When the mag is empty or you're at 10 rounds, immediately start moving.
6. Hit R to reload (2.6 seconds). During reload, you cannot fire — this is your most vulnerable moment.
7. If zombies are within 10 units during reload, switch to the shovel, kill them, then complete the reload.
8. Only use the gatling gun once per wave unless you have a clear reload path.

Sequence 7: Wave Break Optimization

1. Last zombie of the wave dies → 4.2-second timer starts.
2. Immediately check health. If below 100, let regen do its work (don't pick up anything yet).
3. If above 80 HP, sprint to the nearest ammo crate.
4. Pick it up → all guns refilled.
5. Check weapon status. Swap out empty weapons if possible.
6. Reposition to a good starting spot for the next wave.
7. The wave break is also a good time to switch to the shovel for the first few zombies of the next wave (saves ammo on easy kills).

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Advanced Tips

Weapon Tier List by Wave Phase

The 5-Hit Rule

You have exactly 5 hits before death. Each zombie deals 20 damage. This means:

• Every hit reduces your margin for error by 20%.
• At 3 hits remaining (40 HP): one more mistake and you're in critical range.
• At 1 hit remaining (20 HP): the next hit kills you.

Practical application: Treat every hit as a wake-up call. Immediately reposition. Don't stand still to finish a kill if you were just hit — the next zombie is already closing the gap.

Zombie Flocking & Separation

The zombie AI includes basic separation behavior: zombies push away from each other when within 0.85 units. This means:

• Zombies never all pile into one spot — they spread out slightly as they approach.
• This prevents the "instant death by zombie pile" scenario.
• But it also means you can't funnel them into a single point for shotgun blasts — some will flank.
• Use this to your advantage: create space by backing up, which spreads the group wider, then pick them off individually.

Mausoleum Tactics

The mausoleum is the single best defensive position:

• Its narrow entrance forces zombies into single file.
• The shotgun's 24-unit range perfectly covers the approach angle.
• If overwhelmed, you can retreat behind the mausoleum structure — zombies path around it, giving you time.
• During wave breaks, the mausoleum roof blocks line-of-sight from distant tombstones, giving you a safe reload point.

Movement Speed & Kiting

Zombie speed is randomized between 1.35 and 2.5 units/second. Your movement speed is 5.4 units/second. You are always faster than the fastest zombie. Use this to:

• Group zombies into a trailing pack, then turn and fire.
• Circle around the pack to approach from a different angle.
• Lead zombies toward ammo crates so you can pick up ammo while kiting.
• Never stop moving. Every half-second you stand still is a half-second a zombie closes the gap.

Config Tuning (For Advanced Players)

The game has a CONFIG block at the top of index.html. If you want to adjust difficulty:

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FAQ / Common Mistakes

Q: The game doesn't start or shows a black screen. A: You need a modern browser with WebGL support. Chrome, Firefox, Edge, and Safari all work. If it still fails, check that hardware acceleration is enabled in your browser settings.

Q: How many waves are there? A: Technically infinite. The formula is 5 × 2^(wave−1). Wave 1 has 5 zombies, wave 10 has 2,560. The soft cap limits concurrent zombies to 20 at wave 8+, but the total per wave keeps climbing until you die.

Q: What's the best weapon? A: The Assault Rifle is the best all-around weapon — 28 damage, 0.11s fire rate, 72-unit range, low spread, 30-round mag. For close-range crowd control, the Shotgun (152 max damage per shot) is devastating. The Shovel is always a one-hit kill with no ammo cost.

Q: Do ammo crates respawn? A: Yes. 10 crates spawn initially and each respawns 26 seconds after being picked up. They auto-refill all weapons you're carrying.

Q: Why is the gatling gun reload so slow? A: 2.6 seconds. This is the game's built-in balance mechanism — the gatling gun has the highest DPS (440) but the longest reload. Never let the mag hit zero unless you have a clear escape path.

Q: Can I play on mobile? A: No. The game requires a keyboard (WASD + arrow keys + number keys). There are no touch controls.

Q: Is every graveyard the same? A: No. Terrain, tombstone placement, dead trees, lantern posts, and the mausoleum are all procedurally generated each run. No two shifts look the same.

Q: How do I heal? A: Health regenerates automatically after 4.2 seconds without taking damage, at a rate of 4 HP per second. There are no health pickups — surviving without taking hits is the only way to recover.

Q: The game feels too easy/hard. Can I adjust it? A: Yes. Open index.html in a text editor, find the CONFIG block at the top of the script, and adjust ZOMBIE_HIT_DMG, PLAYER_MAX_HP, MOVE_SPEED, or MAX_CONCURRENT_CAP.

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Weapon Matchup Guide

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Changelog & Version Notes

Guide last updated July 2026. Game How To editorial team verified all mechanics against the live browser version.