Allumeria Multiplayer: Co-op, What Works and What Was Broken

Yes, and here is exactly what is supported

The Steam store page lists Single-player, Multi-player, Co-op and Online Co-op for Allumeria, along with Steam Cloud, Family Sharing and full controller support. It is a co-op sandbox, not a server-browser game: you play with people you invite, in a shared world.

The multiplayer fixes that landed in launch week

Co-op was clearly the least-tested part of the build, and the first four patches are full of multiplayer-specific repairs. If your co-op world is misbehaving, update first — these are the known ones, in the developer’s own notes:

• 0.15.0 — fall damage was not working in multiplayer; the boss bar now appears correctly for everyone.
• 0.15.1 — glass shard entities were not working in multiplayer; Forest Keys were not working properly in multiplayer, which is the one that can stall a co-op run at the forest dungeon.
• 0.15.2 — enemy spawn radius was being calculated per player, so a check was added to stop enemies spawning too close to other people.

Still outstanding, and stated as such by the developer: drowning. Patch 0.15.1 changed drowning to 10 HP per breath and noted that it will be moved onto the effect system “for multiplayer syncing soon” — so until that lands, treat underwater sections in co-op as unreliable.

Things that behave differently with friends

• Progression items are shared world state. Forest Keys, dungeon locks and boss summons belong to the world, so one person clearing the forest dungeon changes it for everyone in it.
• Bosses despawn on death. If the player who summoned the Forest Spirit dies, the boss despawns rather than staying up — worth knowing before someone runs in at 30 health.
• Building is where co-op shines. Block shapes, the RGB light engine and the paint roller are all per-block, so two people building in the same room do not fight over a shared palette.

The official wiki also records an old multiplayer exploit around the unbreakable Core block at the bottom of the world, reported for versions up to 0.14.9. We mention it because you may find it referenced elsewhere; we have not verified whether it still works in 0.15, and we would rather say so than repeat it as current.

Performance and hosting

There is no dedicated-server tooling documented, and the system requirements are modest enough (6 GB RAM, 1 GB of disk) that hosting is not the constraint. See the system requirements page for the full spec, including the 2 GB VRAM and OpenGL 3.3 requirements that the store page buries in a footnote.