Gravedigger.io – The Nightshift

Overview

Gravedigger.io – The Night Shift is a single-file, zero-dependency first-person zombie wave-defense game that runs entirely in your browser. Developer eons2eons packed the whole game into one index.html built on Three.js r128: procedural graveyard, six-weapon arsenal, escalating waves, synthesized audio, HUD, everything. No install, no build step, no asset downloads. The only external resource is a single Three.js CDN script tag.

You are the gravedigger on the night shift. The dead refuse to stay buried. Zombies claw out of the ground across a procedurally generated graveyard, and your job is to hold the line as long as you can. There is no final wave. The horde doubles forever, and the run ends when you fall.

Where to play: the itch.io page is author-restricted as of August 2026, so the reliable link is the GitHub Pages build, which serves the identical game file:

https://eonstoeons.github.io/Gravedigger.io-The-Night-Shift/

You can also clone the repository and open index.html locally. Any modern desktop browser with hardware acceleration works: Chrome, Firefox, Edge, Safari. The source code is MIT-licensed, so every number in this guide can be checked against the CONFIG block at the top of the script. That is exactly what we did.

Why it stands out: the entire game was generated from a single AI prompt, then lightly polished. It plays like a competent arcade wave shooter and doubles as a fascinating case study in one-shot game development.

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Controls

The game is keyboard-only. The mouse does nothing. There is no pointer lock, no aiming with the cursor, no touch support.

Two control facts that change how you play:

1. Turning is slow. Yaw rotates at 2.05 radians per second, a full 360 takes about 3 seconds. Never let zombies get behind you, because spinning around costs you two melee swings' worth of time.
2. Number keys beat the T cycle once you own 4+ guns. Pressing 5 for the rifle is faster than tapping T three times mid-fight.

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Getting Started: Your First Shift

Launch Checklist

1. Open the GitHub Pages URL (or local index.html) in a desktop browser.
2. Confirm WebGL works. If the screen stays black, enable hardware acceleration in browser settings.
3. Click BEGIN THE SHIFT.
4. You get a 0.6-second grace period before wave 1. Use it to spot glowing pickups.

First Run Goals

• Wave 1 is a tutorial in disguise: 5 slow zombies, shovel only.
• Locate the pistol pickup. All weapon pickups spawn in a ring 10 to 63 units from the map center, marked by tall orange light beams.
• Memorize ammo crate positions. Ten crates spawn per run, each marked by a green vertical beam.
• Survive wave 1, then use the 4.2-second break to chase the shotgun or SMG beam.

Beginner Mistakes

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Core Mechanics

Health & Regeneration

• Max HP: 100. Each zombie hit deals 20, so you die in exactly 5 hits.
• Regen trigger: 4.2 seconds without taking damage.
• Regen rate: 4 HP per second. From 40 HP to full takes about 15 seconds.
• Hit feedback: red flash (0.35s) plus camera shake.
• Low HP warning: below 30 HP, a pulsing red vignette and a heartbeat sound kick in at roughly 1.6 beats per second.
• The HUD tells you the regen state directly: it shows a "wound fresh" note while the delay counts down, then switches to "recovering" once healing starts.

The regen delay is your biggest tactical constraint. When hit, disengage for at least 4.2 seconds. Kite zombies into a line, break line of sight behind the mausoleum or trees, and only re-engage after the heal starts.

Wave Scaling

Wave total  = 5 × 2^(wave − 1)
Concurrent  = min(20, 5 + wave × 2)
Spawn delay = max(0.22, 0.95 − wave × 0.03) × random(0.7 to 1.3)
Break between waves = 4.2s, grace before wave 1 = 0.6s

The concurrent cap means zombies queue instead of swarming all at once. You never face all 640 wave-8 zombies simultaneously, but you must kill every single one to clear the wave, and the queue refills fast. Wave 10 asks for 2,560 total kills at a sustained pace of about 2 zombies per second.

Zombie Behavior

Each zombie runs a four-state loop:

1. Rising: 1.65 seconds to emerge, tilting up out of the dirt. Harmless while rising, but not invulnerable.
2. Chasing: paths to you at 1.35 to 2.5 units per second, with separation AI and mild tombstone avoidance.
3. Attacking: lunges within 1.55 units, deals 20 damage, then cools down for 1.05 seconds.
4. Dying: sinks into the ground over 0.9 seconds.

The rising-state correction: rising zombies can be shot and shoveled. Hit detection only ignores zombies that are already dying. Aim slightly low while a zombie is half-emerged; its hitbox sits about one unit above its base, so early in the rise your bullets pass overhead. Once it is two-thirds up, it is a live target. A shovel swipe checks flat distance and a 109-degree frontal cone, so you can kill a zombie the instant it starts emerging if it is close enough.

Because the attack cooldown is over a second, a single zombie is nearly harmless; you can literally walk through its swing. The danger is always numbers. Zombies push apart when closer than 0.85 units, so they spread into a crescent instead of stacking. Expect flanking. A fresh zombie also carries a short 0.3 to 0.8 second delay before its first attack, which gives you a small window to kill it before it swings.

Spawning Rules

Zombies do not spawn at random ground points. They spawn at tombstones more than 14 units away from you. The game tries 8 random tombstones for a valid distant one; failing that, it uses the farthest stone it found. Practical consequences:

• Wherever you stand, spawns appear at the stones far from you. Keep moving and fresh groups keep rising behind your old position.
• Nothing spawns in your face. Your closest threat always starts at least 14 units out, needs 1.65 seconds to rise, then needs 5 to 10 seconds to reach you.
• Groans are your radar. Zombies groan every 4 to 10 seconds, so a groan behind you means a spawn you have not seen yet.

Weapon System

Key math:

• Shovel: kills every zombie inside a 2.55-unit range and a 109-degree frontal cone, simultaneously. One swing through a compressed pack of three is three free kills. Zero ammo cost. It stays useful forever.
• Assault rifle: 4 shots per zombie (28 × 4 = 112 damage vs 100 HP). A 30-round mag is 7 kills, roughly 255 DPS out to 72 units. Your main weapon from wave 5 onward.
• Shotgun: all 8 pellets landing deals 152, one blast per zombie. The pellet spread is wide (0.11), so past 12 units pellets start missing. Under 12 units it dominates; past 24 it whiffs entirely.
• Pistol: 3 shots per zombie, tightest spread in the game (0.012). Underrated at medium range when the rifle is reloading.
• Gatling: 440 DPS but 100 rounds last only 5 seconds of continuous fire, then a 2.6-second reload where you cannot shoot. Treat it as a panic button, not a primary.

Aim point: bullet hit detection checks a sphere about 0.62 units wide centered near zombie chest height. Aim at the upper torso. Headshots do not exist; there is no damage falloff either, so max-range rifle shots hit just as hard as point-blank.

Reload mechanics: reloading is keyed per weapon and the timer keeps running in real time even if you swap away and back. Start the rifle reload, swap to the shovel to deal with a closer, swap back, and the rifle finishes on schedule. You never lose progress on a reload by switching. The one thing you cannot do is fire the reloading gun before its timer ends.

Ammo Economy

• Five gun pickups (pistol, shotgun, SMG, rifle, gatling) spawn once per run, 10 to 63 units from center, each marked by an orange beam. Every gun arrives fully loaded and auto-equips when grabbed. Miss one and it is gone for the entire run.
• Ten ammo crates spawn per run, 6 to 63 units from center, marked by green beams. One grab refills ALL owned weapons to full, mag and reserve.
• Crates come back 26 seconds after pickup, and here is the detail most players miss: a respawned crate appears at a new random location, not where you found it. Do not memorize a crate spot and plan to loop it forever. Note two or three crate beams on opposite sides of the map and rotate between whichever are currently glowing.

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The Graveyard: Map Knowledge

Every run regenerates the map, but the layout rules are constant:

• Boundary: a square fence at ±68 units. The world clamps your position at ±66.8. Backing up to a flat wall gives zombies one approach vector; there are no gaps in the fence.
• Mausoleum: sits at the south edge at roughly (0, −42), a solid 4.4-radius collider with its dark door facing the map center. The door is decoration; you cannot enter. Use the building to break line of sight, reload safely, and kite zombies around it.
• Tombstones: placed on a 6.6-unit grid with a 9-unit clear zone at the map center and a 46% skip chance, giving roughly 150 to 200 stones per run. They block your movement, and zombies slide around them with a mild 1.4× deflection. Every tombstone is a potential spawn point.
• Trees: 16 dead trees ring the outskirts between 37 and 65 units from center. Full obstacles for you. Zombies do not avoid them as strictly as tombstones, so do not hug a trunk while kiting.
• Lanterns: 5 flickering posts with orange lights, no collision. Pure orientation aids in the dark.
• Terrain: gentle noise hills about half a unit tall. Cosmetic only; movement is unaffected.

Compass trick: the mausoleum anchors the south wall and its door faces north. Find the door and you instantly know where center is, which means you know where every fence wall is too.

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Step-by-Step Strategy

Sequence 1: Wave 1 Scavenge

1. BEGIN THE SHIFT. Use the 0.6s grace to spot glowing beams.
2. Kill the first 2 or 3 zombies with the shovel (one swing each).
3. Jog to the nearest orange beam. Take the pistol if it is close.
4. Clear the rest of wave 1 with pistol or shovel.
5. During the 4.2s break, memorize: two crate beam positions + mausoleum direction.
6. Do NOT grab the gatling yet.

Sequence 2: Gear Up (Waves 2–3)

1. Wave 2: take the pistol (12/96). Practice number-key swapping: 1, 2, back to 1.
2. Wave 3: find the shotgun and SMG beams. Push toward the rifle beam next.
3. Pickup priority: rifle > SMG > shotgun > pistol > gatling.
4. Tag 3+ crate beams on your mental map, ideally in different map quadrants.
5. Keep moving in a wide circle around center; never camp the spawn-safe middle.

Sequence 3: South Mausoleum Hold (Waves 4–6)

1. Move to the mausoleum at the south edge before wave 4 starts.
2. Stand north of the building so the horde funnels along the walls toward you.
3. Shotgun the first zombies as they compress at the funnel.
4. Swap to the rifle for stragglers outside shotgun range.
5. Take a hit? Duck behind the building. It blocks sight, triggers regen,
   and zombies path around it, buying you 3 to 5 clean seconds.
6. When the south push thins, rotate along the fence to the east or west wall.

Sequence 4: Ammo Cycling

1. Track which crate beams are lit RIGHT NOW, not where crates used to be.
2. When rifle reserve drops below 120 (half), head for the nearest lit crate.
3. One grab refills every gun. Never waste a trip on a single weapon.
4. Respawned crates appear at NEW positions after 26s. Re-scan beams each lap.
5. Route: lit crate → kill along the way → next lit crate → repeat.
6. Shotgun at 12 or fewer reserve? Switch to SMG until the next resupply.

Sequence 5: Health Crisis Recovery

1. Red flash = hit. Disengage immediately, no exceptions.
2. HP 80+: keep fighting, respect corners more.
3. HP 40–60: fall back behind the mausoleum or to a flat fence wall.
4. Shovel the chasers. Free one-hit kills, no ammo spent.
5. Stay untouched 5+ seconds so regen activates (4.2s delay).
6. At 4 HP/s you recover from 40 HP in about 15 seconds.
7. Re-engage with the rifle first; shotgun last.

Sequence 6: Gatling Emergency Protocol

1. Use ONLY when cornered with 15+ zombies closing, or to burst down a
   wave 8+ spawn queue.
2. Fire in 1 to 2 second bursts. 100 rounds = 5s of continuous fire.
3. Pick your escape route after 3 seconds of firing, not after the mag empties.
4. At 10 rounds left, disengage. Start the 2.6s reload only behind cover.
5. Zombies within 10 units mid-reload? Swap to shovel (1-6 keys), clear, swap back.
   The reload timer keeps running while you swing.
6. Once per wave is the rule unless you have a guaranteed reload lane.

Sequence 7: Wave Break Optimization

1. Last zombie dies, the "CLEARED" banner appears: 4.2s free timer starts.
2. Below 100 HP? Let regen tick first, then move.
3. Above 80 HP? Sprint to the nearest lit crate and top everything up.
4. Swap to the weapon that fits the next wave's tempo (rifle default).
5. Reposition: south mausoleum for waves 4 to 6, wide fence-ring patrol for 7+.
6. Open the next wave with the shovel on the first risers. Free economy.

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Advanced Tips

The 5-Hit Rule

Every zombie hit costs exactly 20 HP. Track your health in hits, not points:

A hit is a wake-up call, not a speed bump. Reposition before finishing your current kill. The next zombie is already winding up.

Kiting Geometry

Your move speed (5.4 u/s) is 2.2 to 4 times a zombie's (1.35 to 2.5). The graveyard is your arena:

• Group zombies into a trailing pack by running a shallow arc, then turn and fire at the front of the line.
• Loop the pack around the mausoleum or a tree cluster to compress it, then shovel-swing through the whole compressed line for a multi-kill.
• Route your kiting past lit ammo crates so you loot while being chased.
• Keep the fence on one side of you. An open field behind your back means a second pack can rise there.
• Never backpedal in a straight line. Turning is slow (3 seconds per 360), so rotate in wide arcs instead of spinning.

Fence Wall vs Corner

Backing against a flat fence wall gives you a 180-degree front, with lateral escape in both directions. A corner gives 90 degrees of coverage and zero escape. Corners feel safe for about two waves, then a crescent wraps both walls and you die with a full mag. Hold flat walls, never corners.

Shovel Multi-Kill Discipline

The shovel hits everything in its cone at once, swings every 0.46 seconds, and never runs dry. Three habits make it your economy engine:

1. Compress packs around obstacles, then swing through the line.
2. During any gun reload, shovel anything inside 2.5 units instead of panicking.
3. Open each wave by shoveling the first rising zombies nearest to you. Save the mags for the mass.

Soft Cap Exploitation

At wave 8+, only 20 zombies can be alive at once, but the spawn queue refills every ~0.5 seconds. You need about 2 kills per second to hold ground. The rifle's 255 DPS barely covers 2.5 kills per second, and only if every shot lands. That is where the gatling earns its slot: 440 DPS clears the queue in a burst, the concurrent cap resets, and you fall back to the rifle while spawns rebuild. Burst, reset, breathe, repeat.

Audio Identification

Every gun has a synthesized signature. Learn them and you can play by ear:

Config Tuning (Modders)

The CONFIG block at the top of index.html is fully tunable:

The code framework is MIT-licensed. The game design and branding are not, so mods should stay personal projects.

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FAQ

Q: Black screen on launch. A: The game needs WebGL plus hardware acceleration. Enable it in browser settings and reload. Three.js loads from cdnjs, so the first load needs a stable connection.

Q: How many waves exist? A: Infinite. The formula is 5 × 2^(wave−1). Wave 10 has 2,560 zombies total, though the 20-zombie concurrent cap keeps it playable.

Q: What's the best weapon? A: Assault rifle for general use: 28 damage, 0.11s rate, 72 range, low spread. Shotgun for chokepoints, 152 max per blast. The shovel is a permanent one-hit kill and never leaves your loadout.

Q: I missed a weapon pickup. Can I get it back? A: No. Guns spawn once per run. Sweep the pickup ring by wave 3.

Q: Do ammo crates respawn where I found them? A: They respawn 26 seconds after pickup, but at a new random location. Track the green beams, not the old spots.

Q: Are zombies invulnerable while emerging? A: No. They can be shot once their hitbox clears the ground, and shovel-swiped even earlier since melee checks flat distance and facing.

Q: Why is the gatling reload so slow? A: Balance. 2.6 seconds is the price of 440 DPS. Never empty it without a clean retreat path.

Q: Can I play on mobile or with a mouse? A: No. The game is keyboard-only: WASD, arrows, Space, R, T, and 1 to 6. No touch controls, no pointer lock, no mouse aiming.

Q: How do I heal? A: Automatically only. Survive 4.2 seconds without damage and you regen 4 HP/s. There are no health pickups.

Q: Is every graveyard the same? A: No. Terrain, tombstones, trees, lanterns, and pickups regenerate each run. Only the layout rules are fixed: fence at ±68, mausoleum at the south edge, door facing center, spawns at tombstones 14+ units from you.

Q: The game feels unbalanced. Can I change it? A: Yes. Open index.html, find the CONFIG block, and edit the values above.

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Quick Reference Card

Survival loop:  kite → shoot → regen → loot → reposition
Wave 1–3:       shovel + pistol, gear up, tag crate beams
Wave 4–6:       south mausoleum hold, shotgun funnel, rifle cleanup
Wave 7+:        fence-ring patrol, 2 kills/sec minimum, gatling bursts
Ammo:           10 crates, 26s respawn at NEW spots, refills all guns
Health:         5 hits, regen after 4.2s clean, 4 HP/s
Zombie:         100 HP, 20 dmg, 1.55 range, 1.05s cooldown
Spawns:         tombstones only, 14+ units away, 1.65s rise (shootable)
Mausoleum:      (0, −42), door faces center, LOS cover + kite anchor
Shovel:         109° cone, 2.55 range, multi-kill, free forever

Guide refreshed September 2026. Every mechanic re-verified against the live game source, including corrections to rising-zombie hit detection and ammo crate respawn behavior.