Base Defense: AI Pathing Masterclass
Survival in 7 Days to Die isn't about how thick your walls are—it's about understanding the zombie AI pathing algorithm. This guide teaches you how to exploit zombie behavior to funnel the horde into kill zones where your traps and turrets do the work.
Understanding Zombie AI
Zombies in 1.0 use a sophisticated pathing system that calculates the "cost" of reaching you. They weigh two factors:
- Path Distance: Longer paths have higher cost
- Block Destruction: Breaking blocks adds cost based on block HP
Zombies always choose the lowest cost path. Your goal is to make the path through your traps appear cheaper than breaking through walls.
The Path Cost Formula
| Action | Approximate Cost |
|---|
| Walking 1 block | 1 point |
| Breaking Wood Frame | ~5 points |
| Breaking Cobblestone | ~20 points |
| Breaking Concrete | ~50 points |
| Breaking Steel | ~100 points |
Example: A zombie will walk 50 extra blocks rather than break through one concrete wall.
Kill Corridor Design
The most effective horde base design funnels zombies through a single corridor filled with traps.
Basic Kill Corridor Layout
[Zombie Spawn] → [Corridor Entrance] → [Electric Fence Zone] → [Blade Traps] → [Turret Zone] → [Player Platform]
Key Design Principles
- Single Entry Point: Make one path clearly cheaper than all alternatives
- Funnel Shape: Wide entrance narrows to corridor width
- Stacking Damage: Layer multiple trap types for overlapping damage
- Elevated Shooting: Player stands above the corridor to safely engage
Trap Placement Guide
Blade Traps
- Placement: Head-height (1 block above floor) for maximum decapitation
- Spacing: Every 3 blocks in the corridor
- Power: 20W each—budget accordingly
- Damage: 150 per hit, hits multiple times as zombies pass through
Electric Fences
- Purpose: Stuns zombies, slowing their advance
- Placement: At corridor entrance and midpoints
- Stacking: Multiple fence lines increase stun duration
- Power: 15W per post
Dart Traps
- Placement: Walls facing down the corridor
- Height: Chest-level for torso/head hits
- Ammo: Requires Iron Darts—craft in bulk
- Power: 5W each
Auto Turrets
- SMG Turret: High rate of fire, good for crowds (9mm ammo)
- Shotgun Turret: High damage per shot, slower fire (shells)
- Placement: Elevated, covering the kill corridor from multiple angles
- Power: 25W each
Advanced AI Manipulation
The Drawbridge Trap
Zombies calculate paths based on what they "see" as walkable. Hatches and doors appear walkable when closed.
- Build a corridor with a hatch floor
- Below the hatches, place spikes or a deep pit
- Connect hatches to a trigger (motion sensor or pressure plate)
- When zombies walk onto "floor," hatches open and they fall
The False Wall Trick
Place a door in your outer wall. Zombies see the door as a "cheaper" option than breaking the wall, and path toward it—straight into your trap corridor.
Block Upgrading Strategy
Upgrade walls except along your kill corridor path:
- Outer walls: Reinforced Concrete or Steel
- Corridor walls: Cobblestone (cheaper path, still durable)
- Corridor floor: Wood frames work (they'll walk, not break)
Horde Base Archetypes
The Pit Base
Dig a pit around your base. Zombies fall in and can't climb out. You shoot down from above.
- Pros: Very effective, low resource cost
- Cons: Demolishers can climb out; requires time to dig
The Tower Base
Build up, not out. Zombies must climb to reach you, taking trap damage the whole way.
- Pros: Height advantage, good for ranged combat
- Cons: Spider zombies climb well; collapse risk if base blocks break
The Corridor Maze
Multiple corridors leading to dead ends or trap rooms. Only one path reaches you.
- Pros: Distributes zombie damage, creates confusion
- Cons: High resource cost, complex power wiring
Dealing with Special Zombies
Demolishers
The biggest threat to base integrity. They charge through walls and trigger explosions.
- Do: Shoot the head, maintain distance, use AP ammo
- Don't: Use explosives, shotguns, or let them reach walls
Spider Zombies
They climb walls and bypass ground-level defenses.
- Counter: Overhangs don't work; use elevated blade traps and turrets that aim upward
Cops (Bloaters)
Ranged acid attack and death explosion.
- Counter: Kill at range before they reach traps (acid damages equipment)
Block Strength Reference
| Block Type | HP | Upgrade Path |
|---|
| Wood Frame | 50 | → Wood Block |
| Wood Block | 250 | → Cobblestone |
| Cobblestone | 500 | → Concrete |
| Concrete | 2,500 | → Reinforced Concrete |
| Reinforced Concrete | 5,000 | → Steel |
| Steel | 10,000 | Max tier |
Common Mistakes
| Mistake | Problem | Solution |
|---|
| Building 4 walls | Zombies attack all sides | Create one "weak" entry point |
| Flat trap floor | Zombies avoid obvious traps | Hide traps with hatches/doors |
| No power backup | Generator runs dry mid-horde | Battery bank as buffer |
| Ground-level fighting | Zombies swarm you | Elevated platform with escape route |
| Forgetting durability | Blade traps break mid-fight | Repair after every horde |
Pro Tips
- Test Before Horde Night: Spawn zombies with creative menu to test pathing
- Noise Makers: Speakers attract zombies—place one at corridor entrance
- Emergency Exit: Always have a wood frame ladder ready to escape
- Repair Schedule: Check trap durability on Day 6, not Day 7