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, doubling waves, fully 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 is MIT-licensed (the code framework; the game design and branding are not), so every number in this guide can be checked against the constants at the top of the script. That is exactly what we did for this refresh.

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: Keyboard Only, and What That Changes

The mouse does nothing. There is no pointer lock, no cursor aiming, no touch support. Every input is a keypress.

Numbers that define how the game actually plays:

• Turning: yaw rotates at 2.05 radians per second, a full 360 takes about 3.1 seconds. Pitch moves at 1.55 rad/s and clamps at ±0.95 rad (about 54° up or down). You cannot look straight up or straight down, which matters more than it sounds (see the aim model below).
• Movement: 5.4 units per second in every direction, no sprint, no backpedal penalty. That is 2.2 to 4 times zombie speed.
• Firing: Space is a hold-to-fire key checked every frame. Tapping it at rifle speed wastes nothing; holding it fires at the weapon's true rate. An empty magazine auto-reloads once if reserve ammo exists.
• The world clamps you at ±66.8 units (fence at ±68 minus your 0.42 radius plus a 1.2 margin). There is no jump. The 1.1-unit-high fence rails are scenery, not traversal.

Two habits worth building on day one:

1. 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.
2. Keep your fingers parked on 1 and 2. Shovel (key 1) and pistol (key 2) are your reload-window weapons, and digging out of a bad moment starts with key 1, not with finishing a reload.

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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. The renderer caps device pixel ratio at 2 and runs antialiasing plus 2048px soft shadows, so weak integrated GPUs are the usual failure point.
3. Click BEGIN THE SHIFT.
4. You get a 0.6-second grace period before wave 1. You spawn at the exact map center, facing yaw 0 (north is toward negative Z, where the mausoleum sits).

What the Map Gives You at Spawn

The center of the graveyard is a guaranteed 9-unit dead zone: the generator skips every tombstone grid cell within 9 units of origin. Nothing rises near you at the start, and you can see almost every light beam from center. Spend the first wave reading the map:

• Orange beams (5 of them): weapon pickups, spawned 10 to 63 units from center.
• Green beams (10 of them): ammo crates, spawned 6 to 63 units from center.
• The mausoleum: south edge at roughly (0, −42), a solid building with its dark door facing the map center. The door is decoration; you cannot enter.
• Flickering lantern posts (5): orientation aids. They have no collision, you can walk straight through them.

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, thumping twice per beat cycle roughly every 1.6 seconds.
• 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.

The Aim Model (Read This Before You Blame Your Aim)

Bullet hit detection is not a raycast against zombie meshes. Each pellet projects your camera ray, then checks whether the closest point on that ray sits within 0.62 units of a sphere centered at the zombie's chest, 1.0 units above its feet. Your eye sits at 1.72 units. Consequences:

1. Aim at the upper torso. A shot at head height (2.2+ units) from a standing position passes above the chest sphere at close range. The classic "my bullets went through him" moment is a height mismatch, not a spread miss.
2. Close range needs a slight downward tilt. At 5 units, your eye is 0.7 units above the chest sphere, so you need roughly 8° of downward pitch to center the sphere. Past 30 units the difference vanishes.
3. No headshots, no falloff. The sphere is the only target. A max-range rifle hit deals exactly as much as a point-blank one.
4. Rising zombies are hittable almost immediately. Their chest point starts 1.9 units below ground and eases up over 1.65 seconds. The 0.62-unit sphere slack means bullets connect within about a tenth of a second of the rise starting, but only if you aim low, at the dirt where it is emerging. A half-buried zombie shot at "chest height of a standing zombie" is a whiff.
5. The shovel ignores height completely. Melee checks flat 2D distance (2.55 units) and a 109° frontal cone. You can kill a zombie that is 95% underground by swinging at the screen over it. This is why shovel-first is always correct against risers.

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. The HUD "HOSTILES" counter is exact: unspawned remainder plus currently alive. Wave 10 asks for 2,560 total kills at a sustained pace of about 2 zombies per second.

The wave banner (stone tablet) shows for 2.6 seconds, but the actual 4.2-second break runs on its own timer. When "WAVE CLEARED" appears, roughly a third of your break is already gone. Move first, read later.

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 (see aim model).
2. Chasing: paths to you at 1.35 to 2.5 units per second (speed is rolled per zombie at spawn), 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. Corpses stop blocking spawns the moment the death animation starts.

Behavior details that create your openings:

• Every zombie spawns with a first-swing delay of 0.3 to 0.8 seconds. A brand-new riser that reaches you quickly still cannot hit you for a moment. That window is a free shovel swing.
• Zombies push apart when closer than 0.85 units, so they spread into a crescent instead of stacking. Expect flanking.
• Zombie facing turns at a fixed lerp rate (about 6× frame time), noticeably slower than their movement. Strafe-circle a single zombie and it cannot keep its front toward you; its swing is front-facing only in spirit because the game checks distance, not facing, but the lunge animation still needs the cooldown. The real danger is a group closing from two sides.
• Groans are radar with a 40% filter. Each zombie rolls a groan every 4 to 10 seconds but only actually groans 40% of the time. A groan behind you means at least one zombie you have not seen; silence behind you means nothing certain. Treat every groan as a spawn alert and check your rear arc.

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 roughly 6 to 10 seconds to reach you at zombie speeds.
• Standing near the map edge shrinks the valid spawn ring and concentrates risers in front of you. Center-adjacent positions spread spawns over the full 360°.
• Every tombstone is a potential spawn point, roughly 150 to 200 stones per run.

Weapon System

Key math:

• Shovel: kills every zombie inside a 2.55-unit range and a 109-degree frontal cone, simultaneously, with a flat distance check that ignores aim pitch. 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. Recoil kicks hardest here (0.05 rad per shot), so hold the reticle low and re-center between blasts.
• 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. The gentlest recoil in the game (0.012 rad) means the reticle barely moves; the cost is entirely the reload. Treat it as a panic button, not a primary.

Reload mechanics, precisely: only one reload can be in flight at a time, tracked by weapon key with a real-time end timestamp. 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 by switching. You cannot fire the reloading gun before its timer ends, and you cannot start a second gun's reload until the first completes. An empty mag auto-reloads once; after that, pressing R manually is on you.

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 (pickup radius 1.7 units). 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 with posts every 6 units and a rail at waist height. 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 (7×4×6 box plus roof) 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 jitter, a 9-unit clear zone at the map center, and a 46% skip chance, giving roughly 150 to 200 stones per run. Three visual variants (slab, round, cross), each a 0.55-radius obstacle for you and a potential spawn point. Zombies slide around them with a mild 1.4× deflection push.
• Trees: 16 dead trees ring the outskirts between 37 and 65 units from center. Full obstacles for you (0.5 radius). Zombies do not avoid them as strictly as tombstones, so do not hug a trunk while kiting.
• Lanterns: 5 flickering posts with orange point lights, no collision. Walk through them freely; use them as compass marks.
• Terrain: layered sine hills about half a unit tall, plus 10 cosmetic dirt path patches. Movement is unaffected; the hills only bob your camera.
• Atmosphere objects (400 mist particles, 1,400 stars, moon disc): cosmetic, zero collision.

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 6 or fewer in the mag and none reloading? Switch to SMG until 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 (key 1), 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,
   but the banner ate ~2.6s of your attention. Act immediately.
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.
• Prefer counterclockwise loops if you use the arrows to turn: left-arrow turning (counterclockwise) keeps the pack on your right, in the same direction the camera sweeps, which feels faster than fighting rightward turns against a left-side pack.

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.

The flat-cone check has one more consequence: a swing kills risers that are barely out of the ground. When you hear groans and see dirt moving, walk at it and swing. Two free kills per wave is 6 to 12 rounds saved.

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:

Performance Notes (Weak Hardware)

The renderer is fixed: antialiasing on, device pixel ratio capped at 2, 2048px soft shadow maps, exp fog. If the game chugs:

• Run it in a smaller browser window. The canvas fills the window, so a half-size window quarter-fills the pixels.
• Close other tabs. The sim clamps its step at 50ms, so frame drops below 20fps slow zombies and you equally, but input feels mushy.
• Switching browser tabs pauses rendering entirely (the loop is requestAnimationFrame-driven), which doubles as a pause button. Use it shamelessly between waves; the game has no pause menu.
• The single-file build means zero streaming hitches after load. Once the page is up, your connection does not matter.

Config Tuning (Modders)

The constant block at the top of the script 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. The chest-height hitbox is targetable almost as soon as the rise starts, but you must aim at the dirt where it is emerging. The shovel is easier: its flat cone check ignores height entirely.

Q: Why do my shots miss at point-blank range? A: Height mismatch. Bullets check a 0.62-unit sphere at 1.0 units above the zombie's feet; your eye is at 1.72. Tilt down slightly at close range and aim at the upper torso.

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 there a pause? A: No menu pause, but switching browser tabs halts the render loop, which freezes the game. The window clamp also means alt-tabbing mid-fight is survivable if you disengage first.

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, 9-unit clear zone at spawn, tombstone-only spawns 14+ units from you.

Q: The game feels unbalanced. Can I change it? A: Yes. Open index.html, find the constant 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, 0.3–0.8s first swing
Aim:            chest sphere at 1.0u, 0.62 radius, aim upper torso, tilt down close
Spawns:         tombstones only, 14+ units away, 1.65s rise (shoot early, aim low)
Mausoleum:      (0, −42), door faces center, LOS cover + kite anchor
Shovel:         109° cone, 2.55 flat range, height-ignoring, free forever
Breaks:         4.2s between waves, banner eats 2.6s of it, act first
Pause:          tab switch = frozen render loop

Guide refreshed October 2026. Every mechanic re-verified line-by-line against the live game source, including the aim-model sphere, rising-zombie hit timing, per-weapon recoil values, and crate respawn behavior.