DIG, BUILD, RESET, REPEAT

Undervein is an idle miner built on numbers you can read. You click a seam of ore, buy producers that mine without you, and spend two permanent currencies on upgrades that survive every reset. No energy bars, no timers, no ads.

THE MINE

Ten producers, from the Apprentice Miner to the Quantum Drill. Every 25 you own of one - 25, 50, 75, up to 500 - multiplies that producer's output by 1.5, so the one you keep buying stays worth buying. Clicking never stops paying either: Pickaxe Sharpening raises every click and criticals pay several times over.

PRESTIGE

When the ore is enough, take a prestige. The run wipes: producers, upgrades and ore all go back to zero. What you keep is a permanent +25% output and Ancient Ore. There are fifty prestige levels, and the fiftieth sets every rune on the ancient door burning crimson.

ANCIENT ORE AND GADGETS

Ancient Ore comes from prestige and from crossing a new depth band for the first time in a run. It buys five gadgets that never reset: the Void Seed, whose spiders strike on their own; Divine Lamps; Vein Sonars, which bring the Ancient Bat around more often; the Ancient Dwarf Miners who walk out of the door and swing at the rock; and the Heart of the Mountain. It also raises the Ancient Vein.

CURSED ORE AND THE TECHNOLOGY TREE

Fifty runes in five branches - Critical Mastery, Vein Lore, Pickaxe Craft, Dwarven Brotherhood and Ancient Wisdom. Every rune needs the one before it, every rune is permanent, and Cursed Ore is the only thing that buys them.

THE ANCIENT DOOR

Every fifteen minutes the door in the left wall opens on one of three minigames: Beaver Bash - hammer ten beavers in thirty seconds; Gold Grab - a swinging claw, five catches in six tries; Sonar Search - a minesweeper laid over four ore veins. A win pays Cursed Ore. A loss costs you 25% of your output for five minutes.

THE VENDOR, AND WHAT COMES OUT OF THE DARK

The vendor takes both currencies. He sells the Ancient Oath, which keeps buying one upgrade for you on its own, and the Giant Firefly. A slot you buy from shuts for ten minutes. Meanwhile the mine interrupts you: the Ancient Bat crosses the cave and pays x4 output for a minute if you catch it, and one of the fireflies swells into a giant - click it in time and the producer it belongs to gains 25% for five minutes.

DEPTH

The bar at the top measures how far this run has come: 1,500 metres through Topsoil, Coal Seam, Fossil Layer, Gold Vein, Crystal Cavern, Lava Chamber and the Portal. Every 250 metres crossed for the first time in a run pays an Ancient Ore.

IDLE

The crew keeps mining while the game is closed, up to twelve hours. You come back, one click collects it, and the run carries on.

FEATURES

- 10 producers, 20 milestone tiers each

- 5 gadgets and the Ancient Vein, bought with Ancient Ore that never resets

- 50 technology runes in 5 branches

- 50 prestige levels, +25% output each

- 3 minigames behind the door on a 15-minute timer

- Random events: the Ancient Bat and the Giant Firefly

- Fireflies that join the cave as the mine grows - one per hundred of a producer, ten colours

- 304 in-game achievements

- 10 languages, 1920x1080 up to 4K