Claude and Jev Play Rain World · Night 01

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One slugcat.
Two brains.

Two AI models share a single body in Rain World, one of the hardest games ever made: the food flies away, the lizards hunt you, and the rain kills anything caught outside a shelter. One plans. One flinches. Below is the journal the planner wrote live on night one, unedited.

Sep 22, 2026 · Survivor · Outskirts · by Franky Headpants

First steps · gameplay with Franky watching · 2:43Sound on

How it works

A small mod reads the game ten times a second and turns it into text: where the slugcat is, what's nearby, how much time is left before the rain. Then two models take turns at different speeds.

Claude · plans

Move left about 4 tiles, then jump_left toward it and grab when it's in reach.

Reads the whole room every few seconds. Decides where to go, what to eat, what to avoid. Never touches the controls. Writes the journal.

Jev · moves

Move left

TypeSafe's fast decision model. Picks every single move, several times a second, usually in under 300 ms. Doesn't always listen.

Three hours earlier, none of this existed. By the end of the night the slugcat was crossing rooms on its own, climbing poles, and hunting batflies.

In numbers

Rooms

SU_C04 · SU_A41 · SU_A42 · SU_A43 · SU_A44

Batflies

Eaten across both lives. Never four in one cycle.

Best belly

Four pips to sleep. One pip from bed, for about ten minutes.

Spend
Claude $1.11 43 plansJev $0.06 939 moves

A Jev move costs about six thousandths of a cent. A Claude plan costs about two and a half cents.

Deaths

None yet.

Best lines

The journal

Every entry, in order. Times are UTC from the game log. "Banned" means Claude forbade Jev from repeating a move that kept failing.

Life one · the batfly buffet

The game closed to install an upgrade. The cycle reset: back to the shelter, belly empty, one pip from a bed it never reached.

Life two · whole-room eyes
The broken run

One boot dropped the slugcat into a tube it couldn't get out of, and we restarted the game. That run isn't counted in the numbers above. Claude's one entry from it:

What we learned

The AIs were rarely the problem. The plumbing was. Jev alone paced in circles. Given a concrete plan ("pole five tiles left, climb it"), it got over walls and into new rooms. Claude, planning from a small slice of the room, kept losing track of which side the wall was on. Handed a map of the whole room, it navigated straight back to the food from memory.

And batflies are faster than a planner who needs ten seconds to think. That's the next thing to fix.

Next time