About This Game

Heat is your HP, your fuel, and your timer.

You are a dying star drifting through an infinite, procedurally generated galaxy. Every second you cool. The only way to survive is to slam into other stars and steal their heat.

There is no attack button.

Collision is the entire verb. It damages, it heals, it propels, it feeds your growth. You aim your own body and commit — there is nothing else to press.

Every run is a race against the cold

• Mass growth — Absorb stars to gain mass. The heavier you are, the bigger the prey you can swallow. But mass makes you cool faster, and drags you into the gravity of giants.
  
• Elemental decay — Your composition shifts as your heat drains: Hydrogen → Helium → Carbon → Silicon → Iron. You can read your remaining lifespan off your own body, and each element changes your stats.
  
• The heat death front — A cooling front expands from the origin and never stops. Standing still is death. Keep moving outward.
  
• 34 celestial bodies — Gas giants you can hide inside, ice grains that trade heat for mass, pulsars, white dwarfs, and black holes whose event horizon means instant death.
  
• Roguelite progression — 10 upgrades to pick from during a run, plus a permanent research lab that carries between runs.

No art files. No audio files.

Every pixel of art and every sound effect is generated in code at runtime. Nothing in HOSHIKUI is an imported asset — the stars, their light, and the noise they make are all math.

In the box

• 33 Steam Achievements
  
• Full controller support
  
• 9 languages supported, including English, Japanese, Simplified Chinese, French and German
  
• Under 300 MB, runs on modest hardware

AI Generated Content Disclosure

The developers describe how their game uses AI Generated Content like this:

The game's source code was written with Claude Code, an AI coding tool by Anthropic, under the developer's direction and review.