Draw like mahjong.
Score like poker.Then the mountain changes the rules.

See it played

Four moments, straight off the phone.

Real recordings. Nothing edited, nothing sped up.

Easy to pick up

If you know a Full House, you can already play.

From mahjong: the tiles — three families numbered 1 to 9, Grove, Water and Ember, plus Winds and Dragons — the wall you draw them from, and the rule that a run stays in one family. From poker: the hands — a Pair, Two Pair, a Flush, a Full House, and eleven more.

A round, in three moves

1. 1Take or dig

   The board is six columns of tiles, and only the top tile of each is face up. Take it into your hand, or dig it away to reach the one beneath. Deeper tiles score more, but digs are limited.

2. 2Build

   Keep taking, and discard what doesn’t fit, until your hand holds a formation. The harder it is to make, the more it pays.

3. 3Play

   Play it to score, and reach the round’s target before your plays run out. A round takes a minute or two.

In Japanese mahjong, the wall you draw tiles from is called the yama: the mountain. Here it is the board you dig into, and the game calls it the Vein.

It teaches as you go

Your first round is a guided one. After that, each new thing is explained the first time it turns up on your board — a cracked tile, a Guardian, the Merchant — in a sentence or two, and never before you need it.

Your first expedition is always The Shallows, the gentle road. The other roads open once it ends.

Scoring

Two numbers, multiplied.

Every score is Jade times Echo. Jade is what the formation and its tiles are worth, and Echo multiplies it. Most of what you pick up on the way down raises one or the other, so by Depth 6 a single play sets off a chain of bonuses before the total lands.

(Jade + tiles) × (Echo + Momentum)

Jade What the formation and its tiles are worth. The big number.

Echo The multiplier. Small, and everything on the left is multiplied by it.

Momentum Every formation you play builds it, and it adds to Echo for the rest of the round. Small ones build the most: a Pair builds ten, a five-tile formation one.

That is the trick: the best round is rarely one huge play. Open with a Pair, and the Momentum it builds multiplies the big formation you finish on.

Why you come back

You get stronger. The mountain pushes back.

A full expedition is eight depths of three rounds each. Win a round and you shop; miss a target and it’s over. And just as your build starts working, the mountain moves: your Idols switch off, digs start costing Amber, the formation you lean on scores nothing.

What you build

After every round you win, the Merchant opens. Spend the Amber you earned on:

• Idolsadd to your score, every round.
• Toolsalways on: an extra play, discard or dig each round, and more.
• Offeringswork once, when you tap them.
• Marksupgrade one tile you choose.
• Riteslevel up one formation.

What pushes back

Depth 1

Depth 2

Depth 3

Depth 4

Depth 5

Depth 6

Depth 7

Depth 8

One expedition at a high difficulty, drawn. Each seal is the Guardian at the bottom of that depth; the red marks are the Hexes you carry once it is beaten (at the easier levels, one every other depth). The target climbs too, from 1,075 at Depth 1 to 24,160 at Depth 8 — but your build climbs faster. The number is not the hard part. The rules are.

The Guardians

Twenty-two Guardians. None of them just takes points off.

A Guardian never stops you playing. It takes away the line you were about to play, and leaves you to find another.

A round at Depth 24 of The Further Deep

The Serene One — Echo Capped at 4

Echo stops at 4, and every point above that becomes a little extra Jade instead. The multiplier you spent the whole run building stops paying, so the tiles that add Jade are suddenly the best things you own.

Before the round ends

Five Tiles Exactly Score one formation of five tiles, or the round is lost — even if you reached the target.

Your first formation

No Pair First Your first formation cannot be a Pair. If it is, it scores nothing.

Every formation

No Winds or Dragons Any formation with a Wind or a Dragon in it scores nothing.

In the game these three kinds are called a Demand, an Oath and a Law. This deep, a round carries all three at once.

Choose your pressure

Four ways down, from gentle to no floor.

Two modes. The Mountain is the main expedition: eight depths down to the Heart, on the road you choose. The Further Deep is the same mountain with no bottom, and it opens once you have finished The Descent.

Each road also has nine levels of Intensity, 0 to 8. Win a level and the next one opens: higher targets, a smaller hand, harder Guardians sooner — and from level 5, two extra depths.

The first three are won by clearing Depth 8. The Further Deep has no last depth, so there is nothing to win — only how far you got. New rules land on named depths the whole way down, and the game always tells you which one is next.

What is in it

Plenty to dig through.

The sixty-two are earned, never bought: fifteen tile sets, thirty-six boards, and eleven Idols the Merchant only stocks once you have done what they are named for.

Twelve pieces of story across fourteen painted panels, unlocked as you go deeper.

Make it yours

Same board, your way.

The fit

Why Arcade.