Petri Party is a frantic, physics-driven party platformer where disposable slime prototypes battle it out across a playful laboratory micro-world. Grab a friend (or seventeen), pick your weapon, and dive into fast, high-skill rounds full of grappling, wall-walking and gloriously accidental victories. Built from the ground up for couch co-op chaos.

Up to 18 players on a single machine, plus Steam Remote Play Together (4 player max) so nobody needs to own a copy to join the mayhem. One-hit kills keep rounds short and tense, and momentum-based grappling means the difference between a clean kill and flying face-first into a buzzsaw is all you. Perfect for parties, family gatherings and "just one more round."

Swing from anywhere, run along walls and ceilings, chain grapples to build ridiculous speed, and recover from certain death with a perfectly timed hook. Every surface is part of the battlefield. Ride moving platforms, blast through portals, zip through transport pipes and bounce off launch pads to attack from impossible angles.

Each match is a laboratory experiment on hapless slimes. Go classic in Deathmatch and Team Deathmatch, hog the ball in Murderball, dodge the clock in Hot Potato, fight over the single loaded Golden Gun, race through grapple gauntlets in Waypoint Race, or sink trick shots in the chaotic basketball mode Slimeball.

Bend the rules with stackable modifiers that turn any round into a highlight reel. Float through low gravity, ricochet bouncing bullets off every wall, supersize your projectiles, drop the lights and survive by muzzle flash, or hand the dice to Random Modifiers and let the lab decide. Mix and match for endless mayhem.

Team up for a co-op campaign that drops you and your friends inside Helix Ward-9, a strange research facility with a story it would rather you didn't uncover. Hunt for keycards, unlock new weapons as you go, and fight your way toward the exit. It's a tight, focused adventure designed to be played shoulder-to-shoulder - the same chaotic co-op energy as the rest of the game, with a few secrets buried in the walls.

Arm yourself with weapons spanning every technological era, from baseball bats and rapiers to shotguns, railguns, gravity tools and gleefully oversized ordnance. Each one throws, recalls, launches or fires differently, so picking up the right tool at the right moment is half the fun.

Features

• Up to 18-player local multiplayer

• Steam Remote Play Together support (4 players max)

• One-hit kills for fast, high-stakes rounds

• Momentum-based grappling, wall-walking and ceiling traversal

• 50+ handcrafted deathmatch arenas

• A huge variety of weapons across every era

• Round-changing modifiers for endless replayability

• Multiple party and team-based game modes

• Co-op campaign with weapon unlocks and keycard progression

• Interactive laboratory lobby - test weapons, switches, pipes and teleporters before you play