4★ for the Core Concept

The mechanics are good. It's a challenge to balance between improving the economy and generating heat. It's satisfying when you get it just right, and the resources start to get automated.

Deducting -1★, because it seems unfeasible to reach 0 Population in it's current state (yes, the game is still in a Prototype stage, but getting to some kind of ending should still be possible).

Would like more upgrades for The Pit and The Grease Room, and maybe some kind of Upgrade Cost Reduction-feature in a separate prestige.

Will also need auto-buyers to encourage selling pits (it's currently annoying to restart the last 4 rooms each iteration).

It's close to being a 5★ game, keep at it.