GRAIN ROT Max Players - Party Size Limit
GRAIN ROT max players is 4. Online co-op supports up to 4 players (you + 3 friends). Verified via GamesPress FAST FACTS.
Maximum party size
The maximum is 4 players in online co-op. GamesPress FAST FACTS states Players 1-4 online co-op, which matches the Steam page exactly. You cannot exceed four in a single session.
Solo to full squad
You can drop in solo or fill a 4-person squad. Larger groups handle deeper dives and tougher Corrupted more reliably because they can cover more of the ruin at once.
Why four and not more
The design leans on tight, readable co-op chaos rather than large-scale raids. Four Sparks is enough to create emergent panic without the AI losing track of who is making noise.