Rim Factions

Play RimWorld with up to 4 friends on one planet without the constant desyncs. Everyone plays their own colony in their own save; Rim Factions links your games so gifts, colonists, help, trade and raids travel between them. When you want to play side by side, a live session opens just for that, then everyone goes back to their own game.

Getting together

• One-click join links. Press Play to host your planet; friends press Join on Melty and land straight in a welcome screen: join your colony live, start their own colony on your planet (same seed), or keep playing one of their saves. Steam relays the connection, so there's no port forwarding.

What you can do

• Your own colony, a shared planet. Friends' colonies appear on your world map.
• Call for help. Under attack? Click Call friends for help. Every online friend gets a letter, and one click sends their best fighters to fight beside you as AI allies.
• Trade caravans. Send a caravan to a friend's colony and trade with their real stockpile in the normal trade screen. What you buy leaves their colony; what you pay arrives there by drop pod. Forbidden items stay private.
• Planet-wide assaults. Every few days mechanoids or raiders hit every online colony at once. Colonies that help another earn 300 silver.
• Gifts by drop pod. Send items, silver or even a colonist. Offline friends get them when they're back.
• Trips. Select colonists (and Biotech mechs) and Send to colony:
  • Help (AI): they drop in as allies and come home when it's calm, wounds and all.
  • Raid (AI): they walk in as hostile raiders; survivors who flee come home.
  • Help live: your friend accepts, you join their game live and control your colonists. Send home ends it and both games go back to solo.
• Start together, split later. Invite friends into your colony live; each gets 3 colonists of their own. Later, Leave to found own colony takes your colonists away as a caravan on the same planet.
• Goodwill news feed. Everyone gets a letter when colonies gift, help, trade, raid, split off or change relations. At -75 goodwill you're hostile.

Works with every expansion

• Colonists keep their psylinks, psycasts and royal titles (Royalty), tattoos (Ideology), genes and xenotypes (Biotech) and ghoul status (Anomaly) when they're gifted or go on trips. Mechs can join AI trips.
• Friends don't need the same expansions. Anything a friend's game can't load is blocked before it's sent, with the reason. Looks just fall back to their defaults. Live play needs the same expansions on both sides.

Keeps your mods. Your own mod list stays on. Live sessions use the RimWorld Multiplayer mod with its Compatibility pack (only there can mods not made for multiplayer desync).

Needs RimWorld 1.6 and Steam running.

Credits: bundles, unchanged and with thanks, Multiplayer and Multiplayer Compatibility by the RimWorld Multiplayer Team, and Prepatcher by Zetrith (includes Harmony by Andreas Pardeike), all MIT. Rim Factions itself is MIT and open for remixes. Built with AI assistance.