About This Demo

This is the free demo of Marble Mill.

The copper era and one meltdown, about 20 minutes. It stops right where the silver era would begin.

Wishlist the full game on Steam

Every coin you earn, you can see happen.

No abstract ticking number. A marble rolls, hits a peg, chimes — and a coin pops out. Buy an upgrade and the mill physically rebuilds itself: a new marble rolls in, a new ring bolts on, a bell lights up.

The mill is an instrument

Every hit is pitch-quantized to a pentatonic scale, so the collisions come out as a chime melody instead of noise. The mill changes its tune as it grows.

What's in the demo

• The whole copper era: pegs, bells, and new rings as you can afford them.

• One meltdown: melt the mill into ingots, pick one of three perk cards, and watch it rebuild.

• After that, keep playing the copper mill for as long as you like. The demo has no timer.

What the full game adds

• Silver, gold and diamond. Each era raises the mill's key and unlocks new bumpers.

• A real ending at ~3 hours, with credits, and 100% of the achievements reachable on the way.

• An endless sandbox after the finale.

No microtransactions, no wait timers, no ads.

Good to know

• There is no offline income: the mill earns while you watch it.

• Demo progress is saved separately from the full game.

AI Generated Content Disclosure

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

Marble Mill's text was written with generative AI assistance — the in-game strings, the achievement and perk descriptions, and this store page.

Nothing else is AI-generated. The mill is drawn by the game's own renderer rather than from image files: the build contains no art assets beyond the window icon, which a script in the project generates. Every chime is synthesised in code as it plays, so the game ships no audio files at all. And nothing is generated while you play — there is no AI model in the game and no calls out to one.