Repo ↗ · Source README ↗ · Markdown & license bundle

Image reference (original game): Assassin’s Creed IV Black Flag · original-game artwork, provided by IGDB. Image rights remain with their respective owners. This illustrates the referenced original game, not the actual visuals of this rewrite or mod.

Source maintainer: Kamzik123 · Revision: 68355c71eafa · Catalogued: 2026-10-12

Source license: Documentation license not confirmed · Article: Independent introduction

This is an independently written project introduction, not a reproduction or translation of the README. Documentation permission is unconfirmed or limited in scope. Read the linked repository for the full instructions. Feature and progress claims come from the source documentation and have not been independently playtested here.

AC4Coop is an unofficial peer-to-peer co-op mod for the PC release of Assassin’s Creed IV: Black Flag. It is built as an ASI plugin that requires an ASI loader in the game folder. Two game instances communicate over UDP, and each one spawns a puppet Human representing the other player. According to the README, networking, puppet spawn and despawn, respawning across world travel, and per-frame position and orientation placement are working, with physics disabled on the puppet to avoid jitter.

For animation, the mod uses action replication. The puppet’s behavior component is disabled, and the receiver replays the peer’s action alias, channel and layer. The full 46-slot ground blend array is synced so that walk, jog and run gaits match; the README notes that syncing only a few slots caused the puppet to always walk. Action switches copy the peer’s blend-in descriptor, with optional phase seeking and a minimum blend time to hide network timing.

The README describes the animation side as good enough for now and lists known issues: climbing IK targets are not replicated, phase is synced only on action switch and may drift over long loops, blend-tree transitions do not mirror initial blend factors, character overrides assume both players use the same character, and the puppet disappears in the pause menu. These feature claims come from the README and are not independently verified; the project remains under development.