Frostkeeper: survival in a frozen valley, in early development
A top-down survival game set in a sub-arctic valley in deep winter, where you keep warm, find food, keep a fire alive and plan each day around the weather. It is in early development in Unity 6, and the first step is a look test: one corner of the valley with its weather, fires, night light and snow, judged pass by pass by a human designer while an AI coding agent writes the code.
- Status
- In early development
- Engine
- Unity 6, Universal Render Pipeline
- Survival rules
- Engine-free C# core, tested outside Unity
- Source
- Private, walkthrough on request
What is in it so far
Weather that closes in
Five kinds of weather from a clear day to a blizzard, and the light, wind, snow and sight distance all change together. Sight drops from about 250 m in clear weather to about 8 m in a blizzard.
A fire you can read
The campfire shows its fuel: a fire with hours left burns tall and bright, one with minutes left is a few low flames over red coals. Every stick, branch and log lies in the fire as its own piece and burns down, oldest first.
Light you carry
Nights are dark. The moon follows its real path and phase, a cabin stays dark until a stove or a candle burns inside, and a torch or a lantern makes a small circle of warm light.
Snow that keeps your tracks
Every step leaves a print, and new snow fills it again: light snowfall takes about three hours, a blizzard about fifteen minutes.
A sun and moon in the right place
The sun stands where it would on that date and hour, from NOAA's solar position formulas, and the moon was checked against the eclipses of February and March 2026.
Smooth first
Every addition gets its frame time measured in a release build. The look test draws a frame in about 5 to 6 ms on the graphics card at 2560 by 1440, and moving the snowfall to the GPU took a blizzard's main thread from 8.0 to 5.8 ms.
Relevant if you're looking for…
Frostkeeper is in early development, so it is mainly of interest to survival fans and to anyone making games with an AI coding agent.
- Survival where the weather decides the day: sight drops from about 250 m to about 8 m as a blizzard rolls in, and a fire you can read shows how much fuel is left.
- Weather rendering for a top-down camera in Unity: fog measured from the player instead of the camera, snowfall on the graphics card, and one shared wind for snow, flames, smoke and trees.
- Game development with an AI coding agent: the agent writes the code, captures every pass as pictures and clips and measures the frame time, and a designer judges each pass.
We build this for clients: Custom software and internal tools
How it is made
- 01
Direction
The designer sets what the next pass should achieve.
- 02
Build
The AI agent writes and tests the code and builds the scene.
- 03
Capture
Pictures and clips are captured, and the frame time is measured.
- 04
Judge
The designer judges the files in a gallery and decides what stays.
How it's built
Frostkeeper has been made twice before, first in a web browser and then in Unity with low-poly art. Neither looked or felt the way the game should, so in October 2026 it started again in Unity 6 with realistic art and a camera high above the survivor. The survival rules carried over as an engine-free C# core with its own tests, which run outside Unity.
The weather look is our own, because the weather package we bought barely showed from a camera high above. Fog thickens with distance from the player instead of the camera, so bad weather closes in round the survivor, and snowfall, flames, smoke, trees and grass all read the same gusting wind. The trees, rocks and cabin come from licensed art packs, and the flames are a free CC0 fire loop.
Engineering highlights
- An engine-free survival core in C#, tested outside Unity
- Frame time measured in a release build for every addition
- 80,000 snowflakes placed by a shader on the graphics card
- Weather, fog, snowfall, footprints and fire fuel built in-house
- Every pass judged from captured pictures and clips, never from a live view
Questions
Can I play Frostkeeper?
Not yet. Frostkeeper is in early development, there is no playable build, and there are no dates. The devlog on frostkeeper.agentas.net says when a step is done.
What engine is Frostkeeper made in?
Unity 6 with the Universal Render Pipeline. The survival rules live in an engine-free C# core that is tested outside Unity.
How is Frostkeeper made?
A human designer and an AI coding agent work together, one pass at a time. The agent writes and tests the code, builds the scenes and captures the pictures and clips, and the designer judges every pass and decides what stays.
Want something like this?
Frostkeeper shows how we work with an AI agent on something judged by eye: small passes, every result captured and measured, and a person who decides what stays.
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