ZombieJoiner

ZombieJoiner

ZombieJoiner is a PEAK BepInEx mod that lets the host spawn computer-controlled zombie companions. These zombies are generated in-game, listen to player ping markers, and try to travel to the marked destination by simulating normal character movement.

Features

• Press J to spawn one controlled computer zombie.
• Press K to delete the nearest controlled zombie.
• Zombies follow the latest player ping marker as their destination.
• The zombie AI attempts to reach the pinged point using local path planning.
• Supports direct walking, detours, climbing, jump-grab attempts, gap jumps, and drop-down decisions.
• Includes safety handling for deleted zombies, invalid references, destroyed objects, missing Photon views, and interaction states.
• The spawned zombie is intended to behave like a computer-controlled player-style zombie rather than a normal passive NPC zombie.

Controls

| Key | Action |

| --- | --- |

| J | Spawn a controlled zombie near the local player |

| K | Delete the nearest controlled zombie |

| Player ping | Set the zombie destination |

How it works

When a zombie is spawned, the mod creates a MushroomZombie object and attaches a custom controller to it. The controller reads the most recent player ping marker and treats that point as the active destination.

Instead of using a simple straight-line movement command, the zombie tries to move more like an in-game character. It checks the terrain around itself, decides whether the destination is directly reachable, and then chooses an action such as walking, detouring, climbing, jumping, or dropping down.

The path system is based on several action types:

• Direct: Move directly toward the goal when the route looks clear.
• Detour: Move around an obstacle or approach the goal from a better angle.
• Climb: Attempt to climb when the target is above the zombie and the wall looks usable.
• JumpGrab: Try a jump-grab when the target is above but not directly reachable by normal walking.
• GapJump: Jump across a gap when the landing point appears reachable.
• DropDown: Move down from a ledge when the drop is considered acceptable.
• Hold: Pause or hold position when no safe movement is available.

The controller continuously replans while moving. If a route segment fails, the zombie records that failure and tries to avoid repeating the same bad route immediately.

Pathfinding design notes

ZombieJoiner does not rely on a full NavMesh. The AI uses local probing and player-like input simulation. This makes it flexible in dynamic terrain, but it also means the zombie may sometimes make imperfect decisions in complex areas.

The current navigation approach is best suited for:

• Short and medium distance ping destinations.
• Simple terrain transitions.
• Platforms that can be reached by walking, climbing, or a small detour.
• Situations where the player gives reasonable ping points on or near walkable ground.

The navigation can be less reliable when:

• The ping is placed on a wall, cliff face, or unsupported edge.
• The target requires a long human-style route around the map.
• The zombie must distinguish between a dangerous drop and a safe route.
• The terrain requires precise stamina management.
• The route requires intentionally moving away from the destination before approaching it.

Behavior analysis and known limitations

The zombie follows the latest ping marker as a coordinate, but it does not fully understand player intent. A human player can tell the difference between a wall ping, an edge ping, a platform ping, or a route hint. The zombie currently treats the marker mainly as a destination point and then tries to resolve a nearby standable position.

The local path planner is mostly greedy. It looks around itself and chooses a nearby action that appears useful. This works for simple movement, but it may not always pick the same route a real player would choose. For example, a player may walk around to a ramp, while the zombie may try to climb a nearby wal